Halo 2 in my opinion is the best Xbox game to date. A lot of people are dissapointed because it's not exactly like Halo 1. Well, most sequels aren't the same as the first.
If you were a fan of the first one like I am, then you will more than likely enjoy this one better. It has more weapons, vehicles, not to mention everything has been upgraded. The old pistol is gone, and the new pistol isn't nearly has powerful, so you wont be killed after just 3 headshots.
The graphics have been improved a lot, if you go back and play Halo 1 after playing Halo 2, you will see what I mean. The sound is 10 times more clear, the music is way better too. The controls are the same, you can adjust them to whatever you like.
You can either choose to dual weild, or just stick with one weapon, which makes for different strategies. And on top of all of this is the best feature of all, Xbox Live. Yup, you can now play Halo 2 over Xbox Live. It's easy to use and very fun!
If you thought the first one was great, then go out and pick up a copy of Halo 2, you wont be dissapointed.