High points for theme, I like the out of the box idea use and concept of exchanging the buttons. Didn't take to long to wrap my head around the concept of it. I liked the way all the puzzels evolved and continued to be intersting throughout, although maybe a little too long. Really beautiful grahics too.
My only minor issue is just detection of objects trying to give them buttons, and trying to get other object to move the player would push him off in a differnt dirrection if the angle is not just right.
Otherwise very good job great stuff!