I've given UAE4Droid a try on my Motorola Defy, but controls are fiddly at best since it has only touchscreen input. I only tried Shadow of the Beast II yet. Game runs smoothly but is not entirely playable as the return key is not processed properly.
As for Android phones in general, I would heartily recommend going the Android route. Just make sure you get a phone with a high resolution display (800 x 480 at least). I'm really happy with the Moto Defy. It packs CPU and GPU specs not far from the OpenPandora (OMAP 3610 CPU + PowerVR SGX530, 512MB RAM). Each passing day I feel more smug for buying it.
Cheers!
Edwin
