I've got JamUp on my phone and it's pretty good. It needs a converter for guitar input and headphone output but they are not expensive. Convenience wise it's unbeatable and the maxed out Orange TH30 patch is mega. Admittedly if I had to buy my own phone I probably wouldn't have a relativly new iPhone to run it on but as my work provide one I'm all over it and it ran on the one I had a few years ago so an old one would probably be up to it.
It's usually part of my recording rig by now although I have been thinking about hooking it up to my Palmer power amp and see what kind of sounds I can get through the 2x12". I stopped using it live due to the amount of drunk people throwing their drinks around at the front of the stage and falling on it! I don't think it's sturdy enough to take that. I never really spent enough time with it and a cab to get the best sound.