Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Story: You are a man battling aliens. It is kind of religious. The story is simple but the way it is done is good.
Gameplay: The AI is great and feels real. The Marines act like Marines and even talk to you. But the cheapness of some guns is stupid. You can beat the game just using a pistol and Shotgun and that sucks.
Controls: But the smaller controller for Halo, the sticks work well for aiming but I preffer a mouse.
Graphics: Incredible, these were the best looking graphics I had ever seen the first time I played the game, but the blood is a little cheap looking when you shoot em and the puddle instantly appears on the ground. At least Perfect Dark let the blod expand Halo just splotched it.
Multiplayer: not that good, you can win just by jumping with a shotgun. The story is a better way to play.
Replayability: You have multiplayer and you have a good 1 player mode otherwise not much else.
Overall: A great game, but it does not live up to its hype.