The Level design is actually pretty good. People are saying that it has a simplistic Super Mario Bros type of level design but if they actually played past the first world you would clearly see many big levels with more unique enemies than NSMB Wii & NSMB2. I do think NSMB wii did beat NSMB when it comes to stage gimmicks since there were a lot of them.
I still like the DS version more though because it also had lots of elements from SM64DS like Dorrie the Sea Monster, Unaggi the Eel and some specific enemies like the coin bags and scuttle bugs. Plus the mini games, addictive multiplayer, actual originality and the ability to take the game anywhere beats the Wii version for me personally.
Play it again and remember how awesome it is.
My SSB4 Character roster: http://i1241.photobucket.com/albums/gg519/SVSMX/ssbroster.png
New SMB I wouldn't call it one of the finest Mario titles, however it was a decent first effort, so it can be excused a little.
New SMB Wii took it's predecessor and injected it with steroids. It's a pretty solid and creative game.
New SMB 2...we all know the story on this one already. Shamefully Lazy game.
And I'm starting to feel some disappointment looking at New SMB U. The settings are different, the music is different, there's a new powerup, but I really don't see it doing anything to stand out. It's still more of the same.