Actually this is not too bad. It's a good start that's for sure. Things like this might tend to get swallowed up by Dashboard in the future, how important that is I don't know, but this is a step in the right direction. The author is right when he says there is not enough fun pointless stuff for OS X, i tend to agree with him. OS X takes itself too seriously.
I would say at 10.50% CPU when running just on the dock is a little heavy possibly. The less the better would be...well better!
I think at this stage this app possibly should be free. And the author should look at extending this application into a more customisable animation widget, perhaps with some sort of scripted functionality to it so it could be useful rather than just pretty (perhaps you click on the sprite and checks your email or downloads something for you etc)...
I know there is some ability to customise anyway when you register but a 'pro' version could use more options, like set the scale of graphic if floating, set a number of sprites, perhaps set how CPU instensive it will be etc.
good start though and I think the author is on to something. that is my constructive feedback