Skoove
Skoove is a well-known name in piano learning, but it didn't impress us as much as some of the other apps on our list. While it contains all of the capabilities you'd expect, it doesn't stand out in any way, and we found the interface to be a touch weak in comparison to its competitors.
The introductory course combines a variety of subjects into a simple set of lectures. While the goal is to provide you with a comprehensive understanding of piano as rapidly as possible, the result is that it feels terribly disjointed, and you don't get a chance to ease into any one subject.
While there are some amazing backing tracks on here, and the quality is outstanding, we had a problem with the way the music was read on the screen. It simply runs from left to right, simulating the feeling of reading sheet music, and you have no idea what's going to happen when you get to the end of the stave. Although it is realistic, we prefer the scrolling display found in other apps.
The company has just released an Android app that you can try out for free for a short time.