I've always been a kart racer fan, but never payed much attention to the game at launch. It sounds like multiplayer isn't too populated anymore, but is the game still worth picking up for the single player?

Probably. From what I played more than a year ago, it was pretty good.

This game has always been worth checking out.

Splitscreen is really fun.

Necro, but Blur's only 5 bucks on steam for a few more hours!

It's a great kart-racer games. I can't imagine multiplayer being populated. For singleplayer, however, it's a blast.