Love it. This is a typical nintendo game, extremely high quality and lots of replay value.
My only beef is that if you are too tired to finish a level you have to leave the game suspended or lose your progress (AFAIK). The game only saves on completion of a level and there is no quick save a la SMB2
Still the levels are not particularly long and IMO the game is a must have for my 3DS collection.
Really great work. It runs so smooth. It's so aware of the capabilities of the 3ds. The game just squirts narrative and moods. And the gameplay is super intuitive- like the less you explore or the less into it you are then the less you get out of it because you'll just skip most of the secrets and cool interactions. Its totally made to play your way. Have fun.