Yeah, not impressed with the sound. Impressed with everything else though.
Mario's voice is annoying sometimes. I love the voices in Mario Kart, for whatever reason. "Luigi number ONE!" But Mario saying the name of the game on the title screen is really grating. Random whoops don't bug me, I guess because I grew up more on SM64 than the 2D games.
And I really think that with NSMB and NSMBW they are trying too hard to make "Mario Music" instead of just making a kickass soundtrack.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.