Worked perfectly for me. I like a lot of the scroll to top plugins, but this one was the only one that worked in all pages of my theme.
I know he hasn't updated it in 2+ years, but it's Jan 31st, 2013, and works in 3.5.1 fine for me!
Just in case people don't know ... he zipped it up improperly; he double-zipped it. So you can't just upload the zip file he gives. You have to unzip his .zip file, save it somewhere, then use that zip file. Then it'll install properly.