This app is a great educational tool for modular analog subtractive synthesis. I made my first ever modular patch with this app and it's really not that difficult to do, all you need to know is how a synthesizer functions and have some knowledge of signal flow. Another thing to keep in mind is that there are 2 types of signals the audio signal itself and control voltage. (envelopes are typically CV modules) I would be still using this app, but I no longer have a supported device and I am waiting till I get either a new iPhone or iPad.
I just got this recently but it is so fun to play around with. You can putter with her all day. She sounds pretty god through headphones too. Very moogy. On the other hand I haven't tried to use her in any real music yet.... we'll see hw that goes. I gotta say that sliding virtual cables on touchstreen feels more right than moving them with a mouse. This is a fun, fun little app.