This game is a blast to play! I don't have XBox LIVE, so I am only reviewing the single player and split screen components, but based only on these, this is one of the top tier XBox titles.
Graphics are gorgeous. Each of the levels are a beauty to behold, and the water, as on all XBox games, is perfect. The flame and heat effects off your planes are really cool. All in all, if you want to impress someone with the prowess of the XBox, this is a title to do it with.
Control is very simple. You will be up and flying in minutes. A quick tutorial teaches you all you need to know.
Sound and music are both pretty good as well.
Where this game really shines is gameplay. While its not GTA, it still is pretty openended. You choose which missions you want to complete next by flying near them and pressing 'X' on your controller. The missions are varied enough to keep them fun and to keep you wanting to play.
Multiplayer (splitscreen) is great fun. There are several ways to play, including straight deathmatch, capture the flag, and team variants on both, but my favorite is Wild Chicken, where you must capture a chicken and return it to your base for points. Meanwhile your opponent is trying to shoot you down and steal your chicken. I get a kick out of listening to the female announcer, in an oh-so-serious voice, say "Your enemy has the Chicken." It's great fun. I'm sure if I had LIVE I wouldn't be able to pull myself away, but the splitscreen is handled pretty well for up to four pilots.
Buy this game - you won't regret it!