Terrible... terrible. Probably untested level design. My son played it for a half hour and couldn't make it past the 3rd or 4th jump. As a comparison he is able to beat most levels on "New Super Mario Bros Wii" if given a reasonable amount of time.
The gamepad support was terrible! To jump required moving the left joystick down. Down? It's weird enough that you have to use the joystick to jump instead of a button.... but how is pressing down an intuitive way to jump? The ability to switch to magnet mode wasn't even bound to a gamepad button at all.
Last but not least, the annoying music and sound effects are louder than your average game, so you'll have to adjust the sound in order to feel comfortable with the volume.
So... don't buy this... I'd almost say it's ok to get if it's free (because some people love anthropomorphized animals), but no guarantees.