This is a review based entirely around the full price campaign:
Despite the game looking like Halo and playing like Halo, it still does not feel like Halo.
343 making this game open world and adding a handful of things to do in it does not make it any closer to being Halo. Making Cortana a big central plot point and seemingly writing around the dumpster fire that is 5's story does not make it any closer to Halo.

It provides very little answers to what's going on, and raises even more questions, all while jumping the shark.
If the words "A threat greater than The Flood" baffle you, then you will gain nothing from playing this other than a few hours of killing grunts, elites, and brutes and fighting damage sponge "bosses".
There is nothing to be found here other than it attempting to trigger nostalgia in what feels like a very ingenuous way while introducing you to characters that you'll probably hate or love depending on how sick you are of Marvel Movies.

In short; If Halo was a dead person you loved who had been brought back to life, someone who looks as healthy as they ever have and moves as well as they ever did, but when you speak to them you will realize it's not the same person. That someone else is in there. That the soul is gone and was replaced with something trying to mimic it. While you are often given moments of nostalgia with them you can not help but continue to feel this this is not the same person you loved.That is Halo Infinite.

As a full price game I cannot recommend it. If you're looking for Halo's return to full form you'll only find that it simply plays better than it ever did and nothing more.
If you're looking for that magic, then play MCC or accept that the magic is gone.