First off
The fact that 80 percent of the people who posted here had nothing but negative comments on the game (considering it's thought of as revolutionary, and being called average), just shows that people just want to degrade the game.
The worst thing I've heard though was it being called simplistic.
You shittin' me?
It's the only FPS on console where you can be attacked from the back, but if you're better than the person, can turn around and kill him before he kills you.
Halo 1,2 and 3 are the most talent required shooting games that exist on the console (if not any video game)
Any Halo player that's decent can pick up a Call of Duty 4 game and be great at it in 10 games. Any COD player who's never played Halo would suck after 200, believe me I know I play both, and I averaged 17 kills a game on COD after 10 games.
Oh and the Regen, Bubble shield, and Energy drain were in Halo 1,2 right? Those totally changed the way the game is played.
The only reason people hate it is because they sign on Xbox live, having never played online, but think they are good, and get 2 kills 17 deaths, and it totally turns them off of it. I know the campaign sucks, I've beat it once......on easy, havent tried it since, but it's all about the multiplayer.