Matsu NES is a Nintendo Entertainment System emulator.

Pros:
Reverse playback function (rewind) and Fast forward (0.25 to 16 times)
ZIP file support
Game pad support
Save the state data up to a maximum of 16 slot
Support GameGenie and PAR(Pro Action Rocky) codes
Box art support
Auto search for roms or choose a folder

Cons:
Game play, at the moment, is a bit jerky and the controls are not very responsive. (Tested on an HTC One M8 with PS3 controller)
It is stated on Google Play that this free version has ads... I played with it for about an hour and never saw any.

Matsu NES has a lot of potential with it's easy to use interface and many features. The jerky game play and delayed response on the controller make many games unplayable. If these issues are resolve Matsu NES could be a good NES emulators for Android.