Just needs a hold feature
Took a couple of attempts to get it connected but now I'm using it on an iPhone to control music apps on an iPad and on the iPad to control music apps on a Mac. Minimum latency and simple layout (though the key number / octave strip above the keys is a little too big on an iPhone). Also it would be nice to have a hold feature to make it a 5 star app. Good start though and well worth the price.