In my opinion this is the best Halo out. The levels are truly evolved. The greatest part about this is that you can play as both alien and human. The ending is pretty cool. Plus there are new weapons in the game that causes more damage butt kicking graphics. Especially the part were you can duel wield certain weapons.
In my opinion the magnum is the best weapon. It has great range and good power. The ending of this game is a huge twist. The aliens actually start working with the humans. Halo 3 is going to be a blast!!!
Sneak peak: In Halo 3 there are the weapons from all the games - And the original maps from the first Halo.