This is an excellent game, typical Nintendo creativity all over the place. 3D is directly utilized into the gameplay messing with perspective and what not.
The only issue I have is it lacks replay value or variety. Mario 64 encouraged replaying stages with different objectives, making the maps themselves a hive of activity, enough variation to stop repetition setting in.
Here, you basically just collect stuff. That's it.
Aside from that, it's all good. Everything you would expect from a Mario title. I just wish it utilized the maps more as Mario 64 did.