If you are serious about CNC and want it to last for years then It's everything in a CNC you don't want, and if your thinking to use this for a business then it will be your worst nightmare.

But if you just have limited use for it and don't plan to use it for more than a few years, also don't mind constantly tweaking and adjusting it to hold what would be considered very poor tolerances by a properly built router then I still wouldn't recommend buying it.!

They never tell you about the constant tweaking and adjusting which will be needed to keep it holding pretty rubbish tolerances.?
The linear rails which it doesn't use but rather in place uses cheap V-bearings running on soft angle iron edges quickly wears and gets gummed up with crap causing all kinds of trouble like binding and jamming, esp at higher feeds when torque drops away as the rpm's rise.

The chain drive system is strong but clunky and again as debris gets into it is prone to jamming. As it wears and stretches from the constant rapid acceleration and direction changes it will need constant adjustment and cleaning.

The Z-axis, which the most important area of the machine is a joke, made from threaded rod and angle iron it will chatter like crazy in anything harder than butter.

Then you have the MDF/Plywood frame which will shapeshift more than characters from deep space 9 all mixing into the soup..!!

There's a reason 8x4 machines cost what they do and trying to cut corners just leads to frustrations, believe me, I've built machines for people who have bought these kinds of kits or attempted to build their own and wasted lots of time and money chasing all the nightmare that goes with them before giving up.!! .. . . Avoid like the plague is my advice.