Pretty good app... With some of the sleep tracks, I experienced lucid dreams two nights in a row. The second night was actually a lucid dream out of which I woke up (thought I did). Then woke up from that one too forcefully (lucid again). Its a scary feeling for those who never went lucid...
I knocked one star off because most music tracks are cheesy. Something more tasteful (Vangelis or alike) would make it much better.
Theosoph about Brainwave Studio