Left 4 Dead and Silent Hill, 2 of my favorite games coming together for an exciting, and LONG campaign. But just reviewing the whole map in one go didn't feel right to me, so I'll be rating each and every chapter of this campaign to help sum up my overall thoughts.

When it comes to L4D2 campaigns, I tend to grade them based on these criteria.

General Difficulty How well can a map hit the sweet spot of being a genuine challenge without overstepping into Unfair. A Hard map doesn't = a "Bad" map... unless there's an extreme lack of resources, constant and/or incredibly difficult horde events or just generally poor map design. In terms of grading, I go on a 1-10 basis, but unlike the American educational system, a 7 or lower isn't an "F" for me, a 4 or lower is where I start the bar for Badly designed maps.
IMPORTANT NOTE This map was originally built for the first L4D, and thus the maps were not made with the Spitter, Jockey or especially the Charger in mind. As this is more or less a tuned up port rather then a straight up redesign, I'm cutting the maps a bit of slack in that regard but I'll still be holding particularity bad areas against them.

Old Silent Hill
A solid introduction to the campaign with plenty of goodies hiding off the beaten path. No horde events or fixed Tank/Witch spawns gives the players plenty of leeway to get adjusted to the general feel of the campaign, searching about for items needed to unlock the way to the safe house.
10/10.

School
The first map to introduce what I will effectively call the "Silent Hill Campaign signature", incredibly dark maps that require the flashlight to see properly, general rule of thumb, if a map is or seems to be inspired by Silent Hill at all, play it in a brightly lit room, your eyes will thank you for it. As this is the first of this campaign's Dark maps, it thankfully does a very good job of guiding the players to the school itself and the puzzles inside it are rather straightforward, there are 3 minor horde events, one upon leaving the first alley, another as soon as you walk in the school and the last after you turn on the generator that opens the door to the safe house, all take place close to or within defensible areas and are mainly to add a little extra excitement after the first map. The last can even be outright skipped if the group just bolts into the safe room.
9/10

Otherworld School
The first of the Otherworld Maps, these maps usually have a theme of remixing the layout of the area you were just in before entering the Safe House while adding some puzzles and, true to the source material, being very Dark. This one thankfully puts it's good foot forward, being a rather small map altogether as the group never leaves the school, minimizing any potential irritation from having to navigate in the dark and no random tanks or witches to worry about while trying to solve it's puzzles and collect the keys. Upon reaching the Basement, you have a fight with the first Scripted Tank of the campaign, the room itself has a prop in the center to help maintain distance and block the rock throws, but any stray Common infected in the room can cause some problems with slowing you down and body blocking you.
9/10.

Church
Back outside, it's daylight again and this time you just have to go visit the aforementioned church, which is very hard to miss, to get the key to enter the Safe Room. This is also where the ONLY scripted Witch spawns, right on the inside of the church doors, thankfully a Pump Shotgun is next to a van on the way over so the group will always have a way to safely kill her, provided someone present knows how to Crown. A scripted Horde also spawns after picking up the key, but you're also inside the Church with only 3 ways in, all of which are narrow and easy to cover. Striaghtforward, and frankly rather easy, this map feels like a welcome breather episode after the claustrophobic puzzle gauntlet that was the Otherworld School.
9/10

Hospital
Probably the most straightforward normal map in the entire Campaign, simply run over to the Hospital, grab an easy to find key to go into the basement, turn on a generator and walk into the safe-house. There's only a single building to be found off the beaten path which holds an Auto-shotgun and some other goodies as well as some ammo on a table on the way over with no scripted Hordes, Tanks or Witches to be found.
7/10

Otherworld Hospital
Back in the Dark, this area expands off what the School had done and places in a LOT more items and general backtracking over it's 4 floors, there are also a few holes in the ground that can present a hazard, but most of them are blocked by pipes and thus have invisible walls in front of them. Some of the items spawn Hunter ambushes to keep the players on their toes, and the final key to unlock the Safe Room spawns Boomers to act as a pseudo "Horde Event" that can possibly be avoided completely with solid play. No tanks spawn in here due to the confined spaces, and if there are random Witches, I haven't met any yet. As the midway point the campaign, it hits it's mark brilliantly.
10/10

Otherworld Church
Sadly... it is quickly followed up by what is by far the WORST map in the campaign, it starts off with the group back in the hospital at daytime, now forced down a different path that leads to a Horde event at a Parking garage before arriving at a pawn shop where the group is forced into a fake safe room, and then transitioned into the Otherworld, which on top of being pitch black and thus incredibly hard to see in, is also Very wide open which makes dealing with hordes harder then usual. Upon getting into a mall, you're forced into a fight with a Tank at the bottom of a collapsing walkway before having to cross over a very long, VERY narrow walkway where the flaws of a map designed in the OG L4D really rear their ugly head without a way to work around them, if a Charger or Spitter decides to spawn while the group is crossing the chasm, be prepared for either a tedious roadblock and/or some frustrating deaths. And afterwards you come across a siren which spawns another horde, which then leads to another narrow walkway that thankfully has railings, up to a small rooftop where another scripted tank appears that must be killed for the safe room to be unlocked.
Needless to say, the map is Brutal, downright unfair in a few places and VERY LONG with basically nothing but pure combat all throughout with any full wipes forcing you to have go through all of it again. Those who manage to not quit here thankfully will never encounter anything close to this tedium again in the future maps.
3/10.

Sewers
Enjoy the Fog World while you can, because this is the last brightly lit map in the whole campaign, unless you get Finale 2 or 3. Back across from the Hospital, you head back to the bridge and end up in front of the entrance to the Sewers where upon descending the ladder, it's pure darkness from here on out. Not much in the way of puzzles apart from finding keys and maybe killing a random Tank and/or Witch and no scripted horde or Tank events, just a scripted Boomer ambush after picking up the Safe Room key and 2 hunters on the way back over, an extremely welcome breather after the utter hell that was the last map.
8/10

The Lighthouse
Climbing back up to the streets, the group is now in the entertainment district alongside Silent Hill's massive lake, the entire Kaufmann side quest is still present throughout this area in the form of varies hidden keys and items and going through it grants a ton of supplies and tier 2 weapons. After crossing the bridge at the far end of the district, it transitions to the Otherworld along the docks where you're guided over a rather small path to the lighthouse before backtracking back to the Safe Room. The only map with a variable length, it can be rather short if you just go from A to B, but rewards the curious mind with the many useful items from the pseudo-side quest.
9/10

The Carnival
Going back into the sewers for a brief period before climbing up a long ladder into a rundown carnival, once again the issues of a map made in L4D1 become apparent as the area has tons of instant death drops with a lack of railings to stop a Charger from taking an unlucky survivor over the edge with it, and a random Tank certainly wouldn't help here either. Speaking of which, a scripted Tank spawns inside the Merry-go-round to stand in for Cybil, and the entire thing starts spinning, I don't know if this actually affects the characters but my lord is it disorienting, thankfully the whole place is walled off so no other infected can interfere and you can't be punched off a cliff and the Safe room is right outside once the big guy bites the dust so there's little in the way of worry after the fight is over.
6/10.

Nowhere
The final test of your puzzle knowledge, Nowhere mashes together all the other previous locals into a compact gauntlet that starts with a descent down some, thankfully, walled ladders that bots will still somehow find a way to fall down and die to and from there it's just you, the infected and the puzzles within, which while not really saying much, are the most complex of the bunch, the best was saved for last it seems. Brute forcing them is possible, but wrong answers will spawn hordes, adding a good degree of risk vs reward as there are no scripted events, but frankly, none are needed as the map's quality speaks for itself. A strong lead-up to the finale that's worth it's weight in gold.
10/10

Finale #1
Note: The finale you get is randomly chosen.
This finale is based off the Final Boss arena, a traditional "Stand your Ground" Finale where you must fight off hordes of Infected and kill 2 tanks before the exit hallway opens and you run off into the sunset. The sides of the arena however are pits, and we all know how much Chargers love those, especially when the infected are getting dropped in from the sky. Straightforward and plenty challenging, but be prepared for some ♥♥♥♥♥♥♥♥.
7/10

Finale #2
Or as I like to call it, the "Gate Gauntlet", you run through several compact, fenced off arenas where you fight off infected before killing a Tank to open the way forward to the next, afterward the 2nd falls its a mad dash to the end as an endless Horde does everything in its power to try and stop you from escaping the town with your lives. No instant death potential and normal spawn rules creates a simple, yet solid end to your journey.
8/10

Finale #3
By far the Easiest Finale you could possibly get, you start all the way back in the first map of the game, in an Otherworld version of the alleyway that Harry ran down to find Cheryl, only unlike Harry, the survivors are armed and after gunning down a single horde sized group of common infected, you're dumped back into the real world with no other enemies in sight as you're guided back to the car at the very start of the campaign, which is now fixed up and ready to be driven away. It's as straightforward as it sounds and just as easy as well, in most other campaigns I'd dock it points for that, but given how it's preceded by an absolute marathon of puzzles, infected and potential instant deaths, you'll probably sigh with relief just like I would if you see it. Giving a short cathartic victory lap after the nightmare you endured and survived.
"Varies", Personally a 10/10

Finale #4
A homage to the Silent Hill series famous UFO endings, this ending has you holding out in the Hotel in another traditional stand your ground style finale after a UFO abducts a cow right in front of you, afterwards when the 2nd scripted Tank fight ends, you climb onto the roof so the UFO can abduct the survivors and fly them off to safety. Despite being based on the joke ending, it's also the smallest of the finale maps, and thus is ironically the hardest, but with no cheap instant kills in sight, it's the fair kind of hard, probably my 2nd favorite of the finales behind the above mentioned 3rd. A fun, Fair, challenging end to a lengthy campaign.
Un-ironic, 10/10


Overall
A faithful homage to the First Silent Hill that has tons to do, see and gun down, which, while it does have a few nasty hiccups around the mid-point, is a fun and challenging campaign to tackle both with friends and with bots, which I'd never thought I'd say. I say, give it a shot, but be prepared for a long haul and don't play it in the dark, seriously, say no to eye strain.
8.5/10