Not exactly Paperpile on a mobile, but it is how I use Paperpile on the go.
I dumped the tablet and bought a Chromebook.
Paperpile works as intended. Given that I prefer to type rather than finger paint, there was no real penalty weight wise, but a real gain in functuality. It has a touch screen and makes marking up papers and annotating easy. Most of the benefits of a laptop, and, using Android apps, all the benefits of a tablet.