Mobile Boy is a Gameboy Color emulator for the Android platform. This app allows you to play Gameboy ROMs directly on your Android phone. You can use the pre-loaded freeware ROMs that come with the app, or if you'd like, you can load your own and start playing them without carrying around your Gameboy in your pocket.
This app is very confusing to use at first. The A, B, Select, and Start buttons are all visible at the bottom of the screen. Unfortunately, there's not D-Pad to be found. It seems that the touch screen can be used as a D-Pad, but it's difficult to maneuver around considering that tapping on the appropriate sides of the screen is a hit or miss.
Once you figure out exactly how to control the D-Pad, you'll see that this is a fairly good emulator. It doesn't seem to lag or run into any issues, but then again it is a Gameboy emulator. The fact that it was made means that we'll hopefully see more advanced systems emulated on the Android platform in the near future.
With a lack of connectivity options and save state functionality, it's hard to justify having this app on your Android phone. A Gameboy emulator is pretty cool, but there are far better apps that actually take advantage of the Android hardware that give you plenty of reasons not to get this app.