"Let's get this out there: the body on the gun is NOT durable at all. It is flimsy. BUT considering the price that you pay that is to be expected. Where this gun really shines is its internals. I bought this gun as a spare in case something went wrong with my primary. Performance wise, I was very pleased. I was hitting 385 with only variations of about +/- 2 FPS. I had this gun for about a year and a half and it was used quite often by friends or the occasional kid on the field who's gun broke on them. The outer barrel finally snapped so I had to ditch the body but the gearbox held out well enough to where the FPS is still about 380. I just took the gearbox and threw it into CM body I had lying around and it still chugging along.
Really the only problem I've had besides the obvious weak body was the stock hop up rubber. It is adequate, nothing special, but I'm just so used to my madbull bucking's performance. In my opinion, the hop up unit doesn't really need changing. Even though it's plastic, it's a one piece so it's decent. I had no problems with it, still haven't replaced it. Inner barrel is an aluminium non-TBB, but it gets the job done. I didn't replace it till I swapped the body.
I can't reccomend this gun as primary because it's body is too weak to survive any rigorous play and there are better options for starter guns that will perform decently and are slightly more durable. I would reccomend this for those who need a cheap backup gun, and when it finally breaks, just do what I did and swap the body. Mine is still going strong in its new CM body, well enough that it's become my second most used gun now right behind my ARX. Not a gun I would say "buy it now," but "consider it.""