Simply Piano
Simply Piano is unsurpassed if you're looking to start piano lessons from scratch and are comfortable learning on smart devices like iPads. It makes studying enjoyable while also providing a solid foundation of information and assisting you in learning the piano properly. Simply Piano is ideal for beginners since it allows you to learn at your own pace and set your own goals for what you play, so there is no steep learning curve.
Rather than hammering you with severe music reading and notation right away, Simply Piano simply displays these elements on screen while you're gradually introduced to the act of playing a variety of tunes. You can try it out for yourself with the 7-day free trial, which includes an on-screen keyboard so you can get a feel for how it works even if you don't have a MIDI keyboard (you will need one for the full version).
This is a great approach to get started with the piano because it offers a solid technical basis with no latency and a large choice of background tracks. It isn't as star-studded or comprehensive as Playground Sessions, but it is less scary at first.