Works well ! But it slows down the rendering of pages, and that is with a cache active. Normally, a revisited page is instantaneous, due to the cache. But having this plugin slows it down by a second or so.
Otherwise, love the plugin, but I have to uninstall it due to this. I love it better when a page shows up without any lag, as expected with a good cache plugin.
Hope you can improve it in the future. Maybe it's the jquery effect ? No such issues with ToTop Link which seems to work similarly to yours.