Own a Model 3 Highland now for 2 months, but I'm happy with the build quality.
Could it be better? Absolutely! I think the panel gaps are quite large, the gap between the panorama glass roof and the frame especially scare the living daylight out of me. But overall no creaks, cracks, or weird noise sounds. Even when driving 160km/h it is good enough. Is it on the same level as my previous car (BMW 5 series)? Nope, but overall good enough.
I'm quite impressed with the quality of this Chinese made car; it feels at the same level as my Hyundai Ioniq from a few years back (my first EV), and I remember when Korean cars were crappy too (second gen Kia Sportage, looking at you).