Not terribly impressed. Audio stutters badly, and eventually cuts out completely. Mirroring is quite choppy. Sometimes the server disappears and won't show up in my iPhone's list of AirPlay targets. After enabling and then disabling the window frame, the screen size is permanently reduced until you leave/re-enter full screen.
I've had the video lock up as well, at which point I couldn't get it working again. Tried turning off mirroring on my iPhone, but then my computer disappeared from the AirPlay list, so there was no way to turn it back on. Restarting the Reflection app did not make it reappear.
Based on my experience with the demo, there's no way I'd pay for this. It just doesn't work that well.