A damn good game.
The XBL on this is the best. It is set up just so well and easy to understand. The matchmaking system is great, the maps are great, and the whole XBL experiance on this is great. I know some people who just got so addicted. Thats why I must warn you. You won't be able to put down your controller.
The new weapons and stuff are very cool (The energy sword kicks ass!) In Halo (the first) you couldn't use the sword, but others could.
The ending sucks just to say, its a cliffhanger (I'll say no more) The story was overall impressive but the ending just, ugh, don't get me started!
The whole game is great but when you put it all together, the multiplayer is way better the the singleplayer. Its amazing.