I honestly believe the real Mario will be Super Paper Mario, which will be out on April 9, 2007. Mario in 3D just never made sense to me. 64 was pretty good, but looking back, it had none of the whimsy, imagination, or creativity that SMB3 or SMW had. Sunshine had its bright spots (pun), but I think was a gaming failure.
After spending a lot of time with NSMB and Yoshi's Island, it's easy to see that Mario (the platformer) belongs in 2D. Galaxy might be fun, it might have excellent graphics, but I still get the empty feeling that I always got from 64 and moreso from Sunshine, but that is without playing it. I have no doubt that Galaxy will be a great game, but I think the real greatness will be releasing in just over a month.
*Super Paper Mario hype increasing*