I played Power Drome a bit this morning. WIthout playing campaign you've only got 2 tracks and 2 dromes to choose from in single race. so not much variety till you get some stuff unlocked. it wasn't bad, I'll have to play it some more to unlock some stuff. could be a good multi-player.
I wanted to see how the split-screen would look so I plugged in the extra controllers and set it up for 4 players. There's a lot more available for characters and dromes. However, I didn't look at the track selection, that part may be limited.