I'm on the review for this, and so far I'm finding it fun, though I'm only two bosses in.
It feels like a lesser version of Punch-Out, which doesn't make it bad, it just doesn't make it great.
And I agree with Jonny, why is MotionPlus necessary?
The astute reader will notice that that question was also in the Red Steel 2 interview, and Jason Vandenberghe's response was completely different.