OK. Couple things here. It would be great if there could be a setting for speed. The app is a bit slow to begin each new sequence (uhm, how slow could a random number generating function really be?) - and the actual playing back of the sequence, is dog slow. Some folks might like slow, some folks do like faster - or rather, the ability to choose.
Next, well - as opposed to Simon, there's no different colors, so, all you have is position and musical tone. Unfortunately, the tones don't correlate. I mean, if there's going to be eight tones, at least make them ascending or descending, clockwise or counterclockwise - if not, have them be notes on a scale, with the eighth being the octave. But, as it is now - the two bottom pads have the same note, the only two that do, and the other ones almost, but don't quite correlate, in terms of high or low on the wheel matching high or low note pitch.
So... an odd combination of too simple (slow...) with arbitrarily complex (pads that almost kinesthetically intuitively correlate location with pitch, but not quite) (two pads with the same note, all others different). In short: nice to look at, but quirky. User options to customize all this, and it'd be a fun little game - even worth a buck or two.