The Skyrim itself is a great game in every way (and so does the TES series)! Although it sometimes has some annoy glitches or bugs, but, hey, this is usually unavoidable in game development. Fortunately, it was supported by a large amount of mods and the community, so this is no longer a problem. You can find many kind of mods you like to shape your own world and enhance the comtents of the game (quests, items, NPCs, ...etc). BUT, if you want to do this, you would definitely need A LOT OF TIME (walking through the Riverwood would be the first challenge!!).

• Do what ever you want (Open World)
  
• Main story line with many side quests
  
• Of course, MODS (and CK toolset)
  
• Game systems (skill tree, combat, craft, ...etc)
  
• Beautiful scenes~
  
• ...(maybe update later)

• Some annoy glitches(random CTD, ...)
  
• ...(maybe update later...)