According to the Wii U log I've played NSMB for ~6 hours (including Miiverse, and however it tracks it) over the past two weeks and haven't had a lock up with it. Nintendo Land locked up three or four times in less time. That's just my experience with it. Maybe it doesn't affect NSMB since it's far less demanding than other games.
I tried out the challenge modes and it's fun but there are some bogus ideas. Everything is slow and it's not the loading times. What makes VVVVVV, Super Meat Boy, Hotline Miami, Rayman Origins, and modern challenging games fun is how quickly you can go from failing to trying again without losing the rhythm. For some reason every you fail, or succeed at a lower grade, there's all this junk to slow you down from trying again. Worse is actually succeeding, since you have to sit through the "hooray for you" pose at the end. And worse than that is when you do a little better, because you sit through a longer screen, and another save screen after that.
It's totally sounding like nitpicking out of context. When you're in it, that buffer time between attempts gets annoying. Talented people at Nintendo can make these great games in their bubble, but there are people outside of it doing some cool stuff and it's worth learning a thing or two or three or a lot of things. Options menus would blow their minds.
And I randomly discovered what 99 lives unlocks. I think the Wii game was hat-less Mario. Here, boost mode is gimped by reducing block sizes to a tiny dot. Just in terms of surface area, it's maybe 1/25th what it is before, and disappears after one step. That's something.
Oh, and hey, the game is pretty great if you're not burned out on NSMB games.
