I got a Wii U today. I'm really impressed by the system and what it can do. It is capable of a lot and has the potential to be the next SNES or n64.
New Super Mario Bros U is the only game I could afford, and I beat the main story today after about 4-5 hours of play.
Graphics are crisp and the added benefit of messing with the cool controller make this game a must buy - but unfortunately while its one of the best (if not the best) NEW Super Mario Bros. game, it still commits the sin of being a New Super Mario Bros game. Reliance on star coins as difficulty replacement, not really surprising or wowing at any point, and being more or less predictable prevent this game from ever reaching the lofty heights of the SNES game Super Mario World.
However, its still a great game despite these flaws and it doesn't skimp on difficulty, at least not in the later worlds. Its probably about as challenging as New Super Mario Bros Wii. But I honestly spent a lot of my time yawning and wishing the game could do anything more than give me what I expected of it.
Now, that said... I haven't seen everything the game has to offer. I've barely touched challenge mode and I collected almost no star coins during my first run through. I have yet to try out the game's multiplayer (which will take a while because I lack Wii remotes) and much of the game's content beyond the main story remains untouched by me. When I've experienced it all I will give my overall impressions.
As for the Wii U - great system. It doesn't have that gimmicky flair that the Wii had that made it so special at first. It reminds me of when I got an n64 and GameCube and was wondering what kind of experiences would be in store for me in the future.