i've bought the UCS Falcon Millenium but chinese version and so far, it's been pretty flawless. I'm like at step 230 of 1300ish but atm the difference between lego and this is worth the price. Sure there's a few pieces here and there (1 I had to brute force to make it fit, the other had to be press a bit to stay in place and I'm thinking of glueing the 3rd one, as I dont plan to take it apart anyway) but other than that, it's really the same fun building. Plastic quality is a bit worst, scratch are showing a bit more easely, but if you dont look super close at it, like to the point of seeing the lego logo on the tile, you wont see the difference. And the price difference is more than 3 times less (200 usd vs 700-800 usd in my country) so yeah, no brainer for me.
I also have Barad-dur and the Barge of Jaba to build but I wanted to see first how a fake lego was.
I did the R2D2 too as well as a friend bought it me for my birthday, it was a fun build to do I have to admit.