I almost started a thread for this game after I played the OXM demo, but I wasn't sure if it was out yet.
I don't think I'd call the minigames "a fun diversion at best", because the demo alone had us playing the high jump game for hours. I don't think I've played a single Xbox demo more than twice.
I think this game has the potential of being a GREAT party game in the same way Burnout 2 and 3 were with their Crash Mode. The idea of launching your driver through the windshield may be a gimmick, but holy shit is it fun. The programmers must have realized the same thing, and added the minigames(my theory).
I didn't find the racing nearly as fun, the controls were just too loose. I've only played the demo though so maybe with upgrades the cars handle better. I've got to admire the amount of detructible junk on the course though. If you hit a stack of 100 tires, there will actually be 100 tires all over the place. The cars show damage well too, and yes it's nice to be able to go off the track if you want.