Played the game through on Legendary, then went back and did a couple levels on co-op normal.
I spent the first few levels wondering if I really did enjoy the new Anniversary package. Things that really jumped out at me initially, which I still don't like:
Music pauses when going to cutscenes, never did this before.
No sound options? Really?
Certain music changes during cutscenes happen at awkward, different moments (an example is in the cutscene after you rescue Keyes from T&R, the music kicks in when everyone grabs weapons, now it kicks in about 3 or 4 seconds too late, and it seems to do this in most of the cutscenes with any related music that changes according to action)
Pausing to reload last checkpoint is in a different location, instead of going down one in the menu like my muscle memory says I should, it's the first option. But I got used to this by the end of the game.
In "Halo" right after you get the warthog, you could climb up the wall to get on top of the map, now your warthog magically stalls before you get to the top and you go sliding back down. Lame.
Saw quite a few of the physics glitches where guns get stuck rolling inside of geometry. I don't remember ever seeing this in the original Xbox game, only when it was being played on a 360.
I hate Cortana's model, HATE IT! It's MUCH less expressive than the original model in Halo: Combat Evolved.
One other gripe is in the 343 GS cutscene that reveals the Flood, Keyes is still in his Captain's uniform he wears on the bridge. Pure laziness how Saber couldn't throw his head on top of a body with some combat fatigues like in the original.
I played a bit of multiplayer, and other than the classic playlist, (which only has 4 of the maps on it) the game is still fuckin Reach with all the bullshit that entails, which sucks. Also those MP achievements....
By by far my biggest complain comes with the level geometry on Truth and Reconciliation. There were about a dozen times on that level inside the ship where I would be hiding behind a corner and get shot through the wall. Switch to classic and the geometry I was hiding behind is only about half the size. Or I'd shoot out a door at an Elite and hit nothing, switch to classic mode and there's a part of a door there. Getting spotted around a corner before I could see an enemy. These things happened over and over and it's an embarrassing oversight.
Other than the last one, these are some fairly minor complaints.
Things I love: The enemy models all look amazing. Fighting the Flood is as tight as ever even with the new look. The lighting is so dramatic in so many places and in 99% of the locations you visit, the art direction is fantastic. Only complaint there would be the subtle use of purple in some Forerunner locations.
While I'm no hater of the Library, it does look more interesting and for that reason is perhaps a bit more fun to traverse.
Keyes, my least favorite level in the game, is 100 times better thanks to the lighting in the ground/coolant pool area.
The achievements are great, some of them are fun and I got them by accident or without effort on my first run, others will take hours and lots of patience to get. Pretty good layout on those.
The lonely marine is still there.
I found 4 skulls on my first playthrough, and spotted another I need to go back and grab. A couple of these were in very sinister locations. So I think I have 8 more to find and I'm gonna try to refrain from looking up a guide for a while to see how many I can snag.
The terminals are awesome. I'm missing two though. Lookin forward to finding those and then sitting down and dissecting them through the "Extras" menu option.
All in all, I think 343/Saber did a great job and I'm very pleased with the package. Money well spent and I would have no problem calling this the definitive version of Halo.... any Halo.... Combat Evolved through Reach. This campaign will get lots of playtime from me, moreso than 3, ODST, and Reach combined in all likelihood. The vision, the care it was handled with, and the (mostly) tasteful way the game was updated to Halo 3 standards of Forerunner architecture was handled very impressively, and I have even more faith that 343 will do the Halo franchise justice in their future projects.
Now about that Halo 2 remake.....