Good iPad piano software? I have a third generation iPad ("the New iPad"). I am looking for software I can use to make a piano keyboard appear on my iPad such that when I press the keys, they play notes and sound like a piano. I'd like to be able to use it to plunk out a tune when trying to compose music away from home, and to let my children practice their beginning piano lessons when we're visiting relatives but they don't want to forget what they've learned.

I am looking for the following features:


good responsiveness (no noticeable lag between touching the keys and hearing the notes)
no ads
ideally in the $1 - $10 price range (lower is better unless the program is particularly great, but I'm willing to pay for quality)
doesn't take up too much memory (sorry, GarageBand -- 800MB is too much space to part with on a 16GB iPad)
key size comes close to that of a real piano
reasonable number of keys (perhaps a way to shift octaves if necessary to expand range)
no crazy gimmicks (notes arranged like a piano, not in a spiral or pulsing different colors or other weirdness)


Can anyone recommend software that works well for a use case like this?
Apple's Garageband for iPad is $4.99 and looks like it should fit the bill pretty well. It also has a whole bunch of other instruments and functionality that may or may not be useful for you.

I haven't used either, but Virtuoso Piano (Free) and Pianist Pro ($4.99) look like good bets, based on a quick search and the ratings. Pianist Pro was featured in an iPad commercial, which is probably a pretty good endorsement on its own.