Super Mario 3D World is a great mario game. I wouldn't quite put it in the same leage as Galaxy or Super Mario 64 - but it's definitely a proper Mario game. It's bridging the 2D classics and more modern 3D.
Honestly the worst thing about this game is the name. It's such generic fodder that there's no easy way to tell if this is one of the solid B quality mario games, or one of their best.