A great remake of a great game!
There have been mixed reviews regarding the Anniversary edition of Halo: Combat Evolved. I have nothing but good to say about it myself. The best part are the graphics which are incredible! This is especially evident because of the ability you have to switch back and forth between the old and new graphics. This feature is a great addition and really enforces the idea that the old and new games are practically identical.
They aren't precisely identical though despite what it looks like. The A.I. has been upgraded a bit so the non-playable-characters are a bit smarter, plus there is the addition of a few things like the ability to play co-op, etc. Otherwise the gameplay is pretty much exactly the same, frame by frame, like the original. http://storyhobby.com/reviews/videogames/halocombatevolved