It has 12 instrument, 5 octaves, multi touch support and the width of the virtual piano can be customized according to preferences. You can start from scratch or can use the provided sample songs (2) as well. It has a very minimalistic appearance but and uses little resources too.
To install it make sure you have ...
*. Android 1.6 or above.
*. 437 k of space.
Wanna try it, then go to this official xpiano android market page.