Game is easily worth the $10 -- could use some additional features. Has a good split screen for racing friends.
Decent use of the Sixaxis controller, but I wish it had the option of steering with the stick. Sometimes controlling with Sixaxis can be tedious, but overall, it works well.
My kids love this game (young kids) and with the split screen racing, they can go into 'Battle Mode' which basically is a fight for getting the most 'coins' in a given race.
Single player mode is decent -- you work your way through each course with a time limit and you're supposed to gather as many coins while hitting every checkpoint to complete the race.
Also, very nice use of physics in the game and graphics are pretty good.
Only a selection of two cars, but that is fine for the types of races available. It's a pretty simple game, but it works well and is definitely worth the price tag.