My wife and I personally own iPhone 4S's and PL runs amazing on those and the screen is bright and has good colors and always runs smooth but is a bit small. She also has the first iPad and the game runs great on there as well but it is really big to hold and thankfully I have giant hands. PL has never crashed or froze up on an of my Apple devices, NOT ONCE.

As for the Droid, the app crashes at least once or twice an hour. My wife's company just got the Samsung Galaxy S2's for their work phones and the screen is big so I play on it sometimes (saves my iPhones battery as well). It'll freeze up sometimes during a battle because too much is going on and then you'll have to close the app from the task manager and restart the app. If you push the potions or skills too quickly, it'll crash the app. Granted the screen is great, but when the phone causes me to die often because it freezes, crashes, or responds poorly to my fingers than I get pissed. The S2 just came out so you'd think it would be better. Another thing is that the phone won't charge while you play, the battery will just diminish slower. The iPhone will actually charge while playing plugged in.

The iOS5 from Apple runs PL the best by far but I wish their next phone will have a 4-4.25 inch screen or they'll come out with a 6-7" iPad/tablet.