It's quite fun. It's worth the free download, although it doesn't quite live up to the Wii version.
The control is quite nice to work with, as moving the mouse moves your character. This feels natural and responsive, the only other buttons you'll need are the left button for jumping and the right button for the map.
The music and graphics are generic at the core, but the character has a few interesting properties in its style of animation, you can read about those in other places.
Get the Wii version if you can, but if you're feeling bored and want to give this a try, go ahead. Although the Wii version is just screaming with style, this isn't that bad. I extremely liked the newer release and it just seems to make the original seem much less that it really is.