Halo 2 is a great shooter, no doubt. But it is a little overrated.
I have to admit, I was a little dissapointed in the single player portion of halo 2. It was to short, a little repetitive, and fairly too easy. It did have some intense and memorable moments though, but It needed to be more challenging and alot longer. I beat this game the same day I bought it, and you know there isa problem when that happens. The textures and visuals were pretty decent. Some textures didn't turn out to be right, but that was only a few times. just a few mild glitches. Some of the dialogue was dissapointing. It was a little cheesy. and the marines did not help you that much, either. It seemed like the master chief did all the work. The Single player was worth playing, but nothing "superb".
xbox live:
now the xbox live is a different story. It is revolutionary. Incredible menus, friends lists, clans, and an awesome messaging service. The online multiplayer barely lags, unless someone in your game has a bad connection. The matchmaking service is wonderful. it will find you a game to join no matter what. Halo 2 is probably one of the best, or the best online multiplayer game out there. Along with Far Cry Instincts.
Extras :
The offline multiplayer works great. Up to 4 players can battle it out head to head or do team slayers, CTF, oddball, and many others. There is also a 4 player co-op which works out very nicely.
Conclusion:
Sci-fi shooters should definiltey give this a try. They may be a little dissapointed in the shallow campaign mode, but the online multiplayer will definitley make up for it.