I guess the question is "why is it getting good, but not great scores"? It's got a 83.1 on Gamerankings with 7 reviews.
Is it:
1) The game is not that great
2) The game does not evolve much beyond NGB/NGS
3) There are technical issues (such as the frame rate issues)
4) The reviewers suck at games, and pull a Famitsu and dock points for difficulty
Take your pick. I can understand if it's #2, but don't see how one could justify a significantly lower score.
Of course, Mario Kart Wii has around the same score, and we know how that one turned out. I guess developers are only scoring things on "OMGZ GROUND BREAKING MATERIALZ" and are leaving out any idea if the game is actually...Good.
Back from the dead, I'm afraid.