This is getting better. It no longer crashes, since the most recent update, on Lion. It was unusable here before that.
The full-screen coverflow needs to continue to come along, however. Compositing remains slow. It lags by about 3-4 seconds, with application windows blurred until compositing finishes.
The developer should try to get this along at least as far as Compiz in Ubuntu, including not just basic issues like compositing, but more features like semi-transparency.
One thing everyone is happy with is the dev's responsiveness. That's encouraging.
However, it's hard to justify monetizing this app in its current state.