An action based, highly customizable game with the advantage of online play. A good buy.
The action focuses around the combat system, and the stage selection is limited, but considering the scope of the combat, the stages aren't that limiting. Area size is a little low, but you don't notice that so much as you might if the game were more Halo like. You always want to keep an eye on the enemy after all.
The story is suprisingly compelling, with two or three major twists that really throw you out of your comfort zone.
The online play is great, and the long list of skills you can use makes for a massive veritiy in the gameplay against other players and the in system split screen VS mode means people without XBOX Live don't have to miss out on the multiplayer action.
A solid buy, wither you play it online, or off.