This was downright awesome. The visuals are very nice and polished, the gameplay was really fluent, although a bit annoying in the marble kingdom ;-) The music and sounds were really good as well. I was also really pleasantly surprised by the sudden switch to a point-and-click adventure. Really, really good effort!
Only thing you might want to look into is the isometric platforming. It made the jumps etc. more tricky than it has to be. It was not so much the isometry for me, but the controls (direct direction instead of turning and going forward) and the fact that the camera does not turn when you face another side (goes in tandem with my previous remark). Made it a bit awkward to go 'down left' for instance.
GIven you've been doing this all by yourself makes it even more impressive.