It is a REAL 3D Mario, it just doesn't look like a very GOOD 3D Mario.
It looks lazy, cheap, uninspired, and basically like a portable game in HD. That's just not good enough for a series that brought us 3 of the greatest games ever made in Mario 64 and the Galaxy games.
It's as if the sequel to Bioshock Infinite was revealed as a Call of Duty clone.