Yeah, its really fun, but the replay value and multiplayer is where it shines. There is a story mode where you walk around and talk to people, collect bits, and accept challenges to games from others. You can earn and find bits to buy things like accessories for your character, different discs, scoops, and vehicles. So its always good to run through it a few times so you can unlock/buy everything.
Light cycle races and battles.
Grid tank battles.
Light runner races and battles.
And hyper ball (jai alai)
So its very fun to play with others, and by yourself.