It is most certainly a clone, but people are allowed to make clones, its open source.
The biggest concern would be the USB to Serial adapter, as long as it is supported by your OS your good, from what I can see it should be ok to at least Windows 8+ and probably upto windows 10
As stated, if it works on your machine, who cares. there is no hard and fast requirement to use the FTDI Chip or the Atmel 16U4 or any other for that matter, Some Arduinos don't even have a USB to Serial and rely on an external programmer.
The CH340G usb-serial chip is not used by Arduino. Therefor that board is a clone, which is okay as long and they don't put the name "Arduino" on it. You need to install the driver from the manufacturer : http://www.wch.cn/download/CH341SER_ZIP.html
In the Arduino IDE you have to select the right serial port of course.
The quality of official Arduino boards is good, but the quality of the components on very cheap boards is not so good. In most cases it will work. If you, for example, are going to use it in cold or hot temperatures then it might stop working.
