An extremely fun game, but I'm afraid it has to expand its horrizons a little.
Well, because even with all its polish, Halo 2 is just another game where you run around and shoot things. There aren't any kind of variety to the missions either. You basically run from point A to point B, blasting everything in sight. This gets repetitive after a while, especially since the level design isn't always that great.
Oh, and while we're on the subject of critisisms, I absolutely hate the Energy Sword. It makes certain parts of the game way too easy.
Complaints aside, this is probably the most entertaining game you'll ever play.