Mstly everything. Its quiet, doesnt break balls, good distance, great speed, light, and looks cool.
It leaks a tiny bit of air. Probably 1 or 2 oz. a day. The stock barrel needs to be replaced after you go a few times, because its not extreamly accurate. Thats all I can think of.
This is a great gun. If your looking for a good gun in a fair price range then this is it. After a few times going you might want to look for a new barrel though. The stock barrel is very short and doesnt look very good.
Im glad to hear your Griffin works, my Dad baught one online and it gave us nothin but trouble ( until we sold it), the balls broke so much that if you didnt pay attention the paint would clog up the barrel as if you had just smashed a tropical bug the size of my fist. this however was probably due to personal error or a rare defect.