A great game all together, but falls apart in some areas.
In the multi player portion, there are some pretty cool maps and even some early favorites remade like blood gulch, battle creek, longest, and about 3 more but they all have new names and a halo 2ish feel and scenario. If you have Xbox LIVE, you'll definitely enjoy it, since the gameplay for the most part is decent. There's a new lock-on feature with weapons which is good for beginners, but is really something that should be able to be turned off.
As for the weapons, there are many new one's which adds alot of variety. The assault rifle from Halo 1 seems as if it was split and taken away to make the battle rifle and SMG. The pistol was taken away to put in the magnum which doesn't have a scope. The Rocket launcher can lock-on to vehicles, which is a cool feature, but require's no skill. There's around 4 new covenant weapons you can use. Including a new covenant rifle and sniper rifle. There is also dual wielding in which you can hold 2 of the smaller weapons at the same time.
Another new feature is the destructible vehicles. There are also more vehicles to use and even one new to the game. You can now use the covenant tank, the Wraith, and the Gauss Warthog which shoots rockets, which was only a vehicle in Halo PC. The new vehicle is the Spectre, it holds three players and seems like the covenant version of the warthog. All the vehicles from Halo 1 are back, if you had any fear of losing them.
Overall, Halo 2 is a great game which should not be overlooked. Sure it has it's flaws, like every game does, but nothing as serious as to hate the game for. This should definitely be a game for you to buy if you have LIVE, or if you're considering getting LIVE. For the most part, don't buy this game unless you have alot a friends to play it with or really -and I mean really- like killing in campaign.