The funny thing is, it sounds like the 3DS game is pretty much exactly what it looks like. A bunch of younger developers were trained very specifically in the art of Mario level design and then allowed to build a whole game's worth of stages. The result is a game constructed -- possibly very skillfully, possibly not -- almost entirely out of existing concepts and assets. No one got to create any new pieces. They probably don't even have the authority to do so. They just got to arrange the pieces as creatively and inventively as they could. New Super Mario Remix.
The Wii U game looks a lot more interesting, probably because it's being made by people with the authority to mix things up a little. (Hopefully they actually use it!) But man, you take one look at a game like Rayman Legends -- a game with screenshots that look like they're paintings ripped out of a Rayman Legends concept art coffee table book -- and it's hard not to feel like even the Wii U entry just isn't trying very hard.