You start off in freestyle mode with a black canvas in front of you, and as you tap on the screen, piano notes play in a random sequence. Hit the icon on the upper right and the piano becomes visible in a spiral form. Now it's time to recreate that Chopsticks scene from the movie Big!
A song book helps turn your random mashings into beautiful music, but this is by no means any way to learn the piano! Click on World and you'll see why, as Smule allows you to eavesdrop on the terrible music being created by others from around the world. Fur Elise has never been so abused!
Magic Piano is definitely a curiosity, but a cool one at that. Don't expect a piano teacher, don't expect a music game, just expect to have a bit of fun while trying to make some music.
Good: nice interface, fun to listen to your music and others
Bad: would have been nice to have more songs, more connection to the piano
Quick score (and corny pun): 4 out of 5 conductors agree, you should probably spend some time learning the actual piano, (but it's still fun)!