Pianist HD could well be the most complete app for those playing the piano or those wanting to learn to play piano, as it offers many features other music apps don't and it allows you to play keys in six octaves.
Once installed, Pianist HD provides you with a handy six-minute YouTube tutorial that takes you through the many options this app offers. The app also offers small tutorials the first time you open any of the menus, which is a nice touch, too. With just a bit of practice you can play many well-known songs using the "Song Book." You can also choose to play other instruments including the drum, violin, guitar, and flute in the "Instruments" section. The app responded well to touches (keystrokes), which is vital for an instrumental app. The Settings menu gives you many options for customization. You can adjust anything from the playing speed to the looks of the keyboard. A rather unique function of this app is its "Double Keyboard" option, which allows you to place a larger range of keys on your screen, making it easier to play certain songs. You can record your masterpiece with just the click of a button and save it as a MIDI file.
Pianist HD is a full-fledged instrumental app that will be a joy to use for anyone from the average Joe to musicians who can't carry their piano with them everywhere they go, but can't keep their fingers still, either.