It is rather hard to criticize - it has only one level.
The overall feeling of it was nice - things worked fairly smooth, and bugs were not numerous (pressing space near the button results in standing on it upside down; character didn't die from visual hit by turret bullet).
This can turn into a nice puzzle platformer. Just work on it, and make it more colorfull.

Unfortunately, I've not worked with 3dGS for a while now, but it was fun