Surprisingly fun--much better than I expected.. Very responsive, gnarly synths, lots of presets. Seems to be written in Flash so there are a few oddities, e.g. when quitting you won't get a warning to save an unsaved composition, the app window always opens at the default size, et cetera. The keyboard animation didn't work on a few of the presets, and I don't get the keyboard mapping--the documentation is currently scant, but under construction. I am confused by the 'Install. AudioSauna." command in the Help menu. Maybe this installs the dashboard version? I dunno. AudioSauna makes a lot of network calls to advertisers as the app is ad supported. The ads are easily dismissed after each launch of the app. If it could read or write MIDI files it might rival some "real" apps.