John's emulators are arguably the best on the Google Play market.
There is a HUGE problem with the cheats. Some times you can enter them, then they disappear after some time. Then, sometimes it doesn't even let you input the codes and it says "error, code not valid."
I love this emulator, and I've been using it forever, but the last update or so has somehow made it uncompatiable with my moga wireless controller. I've been using it fine up until now. please bring moga support back.
Best emulator, easy to use!
emulates games very well. i played Pokemon for ~20 hours during some long road trips and it worked very smoothly with minimal hiccups. my only gripe is that since there is no tactile feedback like there is with physical buttons (on an actual Gameboy) it can be easy to misplace your fingers when trying to use the d-pad and this can be pretty annoying when playing a game that requires constant use and navigation of the d-pad like Pokemon. this is an issue because of the inherent nature of a touchscreen and not in any way indicting of this app though.
-added new Dropbox feature(requires John DataSync v2.00)