You'll have several different spaces to save your game, the option to speed up the game's speed, tactile buttons, and, of course, the possibility of uploading ROM's (the game images) directly from a compressed file that has been previously placed in the games folder.
This means that to be able to enjoy the app you'll have to download the game's ROMs separately. Having the emulator installed on your phone will be pointless if you don’t add some games to try it out.
Gameboy Color A.D. is an excellent emulator that works pretty well on just about any Android device. Although if your phone is relatively old most games may run very slow...if they run at all.