I have an X3. You basically will get what you pay for. Whirlpool forums has perhaps the most users for the X3, I'll link here
Pros:
Price
Picture Quality (though Qdot is basically a sham, just like Samsungs)
HDR is good, not the best, but if you have never seen HDR content you will be impressed
Sound, though it lacks punch the built in sound is very good
Micro-dimming. Though this is an edge lit panel, turning this on will produce some difference. Note it does not play nice with all HDR content.
CEC works
Voice commands work very well
Cons:
This is a edge lit panel, thus no FALD
Being edge lit, back light bleed is an issue. (whirlpool link has some pictures)
Judder reduction usually causes more problems like on most panels. The set will have issues appropriately playing formats that is not native to its refresh rate (60Hz).
Android OS. This is not TCL's fault but is inherent to all Android TVs (sony included). The responsiveness is not the issue, neither is stablility it is the quirks e.g. some ports simply stop working, requiring a power-down to bring them back to life. Some apps can't be removed.
I have not seen a better 4k HDR TV in its price, even in Australia (Except maybe hisense). But remember you do get what you pay for.
If you can afford an OLED go for it. Though it has its own set of specific issues. There is not much of a difference between Samsung QLED and this TV in terms of features, but there is in terms of what you spend
Whirlpool
http://forums.whirlpool.net.au/archive/2648438
(has both X2 and X3, X3 being a curved version of X2)
NOTE: The only Full Array TVs by TCL are there US specific models (Specially the Roku models)