"Learning the piano" is nothing like Guitar Hero, though. These apps just tell you (and check) which key to press in what order. They don't teach you anything about musicality like dynamics or articulation. They often can't even tell if you played multiple notes simultaneously or if your timing was correct.

If you cannot already play the piano, what you get is just a fancy way to learn reading (parts of) sheet music with the ability to connect a MIDI keyboard.