I messed about with this a bit too, it's really interesting what it does and doesn't work well with.. If you have something that's already got quite a lot of frames it just makes a mess of it generally, and sometimes things with not so many frames you get an odd ice-skating like effect? It's very very cool though as a basis, and after cleaning up its results could be super useful.
I'm planning on using it on some of my flying enemy animations, just, putting the keyframes in and seeing if it does an ok job of inbetweening them.