"TL:DR This is a good gun. You're paying for a SOLID receiver/frame/rails/stock/grip. The internals are adequate, but will take some mods to get this thing running with the big ($300-$400) guns. Namely, you'll want a MOSFET, better motor, and bearings.
Now to the detailed review:
I bought this gun as a starter, and after having this gun for awhile, and disassembling/upgrading, I think I can provide some good info on it.
First off, it's a SOLID piece of hardware. This had a lot less stock wobble than any other gun I've come across, including my friend's brand new Krytac. The only rattle from this gun is the BBs in the mag, and the dummy gas tube over the barrel.
The gas tube is easy to remove (once the flash hider is off), and I recommend doing so. Just unscrew the set-screw in the bottom of the gas block up front, and remove the gas block and metal tube/rod. Done.
I got the tan version, and the receiver, rails, and buffer tube are all metal.
The plastic bits (stock, grip) all appear to be nylon, which is much more flexible and durable than ABS. The gun itself will withstand some abuse.
The stock will fit batteries pretty well. Plenty of room to spare on both 9.6V NiMH and box-type Lipo 7.4Vs.
Tenergy and Tattu branded 7.4V batteries work well with this gun, but you'll want to get bearings in the gearbox to extend the life (see below).
The outer barrel is 14mm left-hand threaded, but the flash hider is glued on. You'll need to break the flash hider, pull its roll pin, AND get the glue out of the threads in order to attach anything to the muzzle (tracer units, etc.).
Now to the internals. This is pretty basic, no-frills stuff. Your money is paying for a solid chassis, not fancy internals.
The gearbox appears to be a bone-stock, rear-wired JG 8mm version 2. It has bushings. It has normal trigger contacts. It has a small Tamiya connector. 'Nuff said.
Upon disassembly, it was adequately shimmed. Not perfect, some side-play in the gears, but it wouldn't have died prematurely from poor shimming. Nothing was rubbing that shouldn't have been. The motor can be tweaked to slightly better position, too.
The first thing I did was put bearings in it. That made a world of difference.
Out of the box, 7.4V lipo batteries would fail to cycle the gun (couldn't compress the spring) long before reaching minimum voltage. It didn't take long for them to wear out, either (maybe a couple thousand rounds?).
Once I switched to bearings (8mm), I could get a full day of skirmishes out of the same batteries, and the fire rate was much more consistent from beginning to end.
The motor is also adequate, and not much else. Classic Army or Krytac motors will run rings around it. Stock, I'd guess it's shooting in the 10-12rounds-per-second range.
The motor was my second upgrade. The MOSFET was my third.
I heartily recommend this gun if you want a cheap "in" to airsoft, and you're not afraid to upgrade later. With the upgrades in it (MOSFET/motor/bearings shimming and some TLC/service), this will run with guns $200 more expensive. And you can get all those mods for _$200, plus some elbow grease.
5 stars for the money (sale price). 4 stars if you pay over 200 for it.