You can't ask for a better arcade racer with real cars.
First, in career there are nine rivals to unlock and beat. You can unlock them by doing well in races and recieving lights for winning and you must meet that rivals demands. Demands are specific things that that rival wants you to complete like earning a certain number of fans.
Fans are a fun way of tracking you progress in the game. You earn fans for almost anything and if you get enough in one race, you get an extra light for reaching the fan target. Also, if you complete the fan run, an optional part of the race, you get another extra light. Fans are important for unlocking cars, since every time you move up a level you get one or two cars.
In Multiplayer, you can play up to four player split-screen local, or if you alone you can play on Xbox Live. On Xbox Live, there are nine events to play in, but you only have access to two or three at first. The higher rank you are the more events you have access to.
Overall, I think Blur is a great game because it is unique but also has a ton of stuff packed into it. I'm a Mario Kart fan and a Forza Motorsport fan, so this game is a great combination.