I give the Gaui 330x 7 out 10 because it has a very solid body very durable, inexpensive when compare to the other quadcopter on the market and it actually flies.
Pros: parts are easy available, it's simple to build and repair. The main brain on this copter consist of a Gyro and receiver. That's it nothing else, performance is pretty good as well. There's also talk of a gps on this quad. I was able to fly this quad in my dinning room which is 12'x12' with no problem.
Cons: Cheap esc and brushless motors, horrible landing gear and propeller nuts that may come off even if loctite is used. For example i had a propellor come off while checking my transmitter setting and i used loctite.
I recommend replacing the propeller nuts before any major flight this will save you a lot of money on repairs if one or more propeller come off while in the air. Later down the line change out the landing gear other than that buyers should enjoy this quad.
I have posted photos of the locknuts i used to replace the propeller nuts, my 330x start to finish. If you have any question on building or in general please contact me.