I have this. It's not bad, but there's not very much content even with the DLC stuff they've released. You can see everything in an hour, maybe less.
The vehicles are well-designed and amusing, but the big problem is that since you get way more points for destroying vehicles than you do for completing laps, you're always driving really slow so you can drop mines off the back of your vehicle and blow up your pursuers. It's not very exciting.
There's multiplayer, but I could never find anyone playing. With this free weekend there might be some people online. Time to get some online achievements.