Pros:

Rather Accurate to the original Mario 64
Interesting way to get to Bobomb Land.
The Dead Goombas are awesome. More Dead Mushroom Kingdom Denizens would be welcomed.
The Jumping to get items out of Blocks is great. More of the Question Blocks would definitely be welcomed.
The Boos that are only Visible Under Flashlight are incredibly awesome.
Incredibly surreal.

Cons:

Zombies are sort of ranging about in the open doing nothing, and except for in the Sewers, there's really no surprise or Challenge to Zombie Spawnings.
The pathfinding is somewhat confusing as to where to go.
The way to open the gate onto the mountain is hardly noticable at first.

Conclusion:

Could be considerably improved. Zombies climbing up the mountain after you, or jumping down at you as you climb for instance. Try using Elevation to your advantage for zombie spawnings, place them out of sight and have them drop onto the survivors or come from below.
Lighting cues to help path finding navigation would be helpful as well.