It works perfectly on an iPod Touch 5g--no delays and the button sizes are big enough. A deliberate, steady strum makes fine music. Of course this app does not replace a real Autoharp (get one if you can--I love mine), but it is fun for chord progressions. You dont need a songbook for chords because most songs are available online for free.
Corvus.Corax. about Musical Autoharp