I had this in my CA AUG, before i replaced it with a KA Infinite Torque Up. Now it's in my G&G/Cyma AK-104, and it's doing a very good job still. It is a bit expensive, and there are cheaper alternatives, but it is a good motor. With standard ratio gears pulling an M120 spring, i got nearly 30rps with a 3600 mah ni-mh battery, I would say that's pretty good.
It's quite powerhungry, but if you feed it with a good battery it can pull fairly heavy springs at a good rate of fire. The stock pinion gear could have been better, it didn't take long to wear it out, but replace it with a good aftermakret gear and this motor will be very reliable.
Reliable, this motor will handle an 11.1v li-po.
Well built, this motor is sturdy and can take some abuse.
Weak pinion gear
A bit whiney