That's why we spent quite a bit of time on making interesting metrics that show your progress over time, even if it is small per increment the overall effect is substantial.
I had good experience with Android app made by soft²cat, but it long gone. Unlike other guitar-hero like apps, it waits for the note to be pressed, so I cannot miss it, and the app discards the note when I press the note earlier. It allows me to play melodies at my own tempo: slower or faster than the original, which is much easier for me.
The rate at which piano teaching apps come and go was one of the factors in our decision to ensure that the app would also work 'stand alone', it's just straight javascript and will work from a zip file taken from the repository. Just unzip and play, no toolchain required.
We purposefully chose not to make 'an app' right now but to work in the browser, this gives us a different form factor to play with and some pretty powerful tools to get to the point where we really understand the space well enough to make a move. Think of the present project as a study, a way to have a zero-tooling set-up that allows us to work on this without having to worry about platforms and other fast moving targets. The idea is to first make it work very well and to address all of the valid concerns raised in this thread (of which we for the most part were already aware, but HN wouldn't be HN without its brutal reception of any piece of work). Then when it is bullet proof against such criticism it can be launched to a much larger audience.
