picked this up a couple days back for $39.99 at circuit city.
it's great! not warioware great, but probably right behind wii sports in terms of tilt. or maybe i liked warioware so much is because it's the first real "for fun" video game i've picked up on a console in... 15 years?
multiplayer is absolutely fantastic. my wife and i have very close battles! especially the sprint mode, since you could be leading and then all of a sudden you get stuck on one and lose. i'd say it's almost too exciting!
haven't gone through all of the modes yet (gone through 1 of each attribute), but it looks like there are more than just the 15 categories reviewers tell us. looks like some need to be unlocked.
sales: MP8 is #1 on Amazon, after like 2 weeks, this is currently #18 on Amazon. so given that MP8 sold 300k+ in its first week... expect this to sell ~70k in its first week. it should have very long legs in the US.
the Wii is an epidemic.