I'll start with the flaws and the distribution of the pieces in the bags.
The bricks with many pieces are in separate bags, and that's fine. The numerous bricks with few pieces are literally thrown haphazardly into numerous bags where you literally have to curse, especially to find the smallest pieces.
Then some bricks aren't the color they should be. The problem is relative because they are pieces that won't be visible in the end, but the instructions only list a few different colors, while others aren't. Or rather, some white pieces are few and run out, and you have to use the gray ones. But to be sure, I checked all 540 pages of instructions to see if I could use a different color!
While assembling, some pieces fit together poorly (like the joints), some pieces fit together with difficulty, while others miraculously stay together because they're soft. This becomes a serious problem because when you start turning the spaceship up and down (during assembly), various parts keep coming off, and you're forced to glue some bricks back together. I never thought I'd have to use glue with bricks. Obviously, this huge problem wouldn't exist with the original Lego bricks.
Some pieces aren't exactly the same shade. Many of the gray pieces that make up the spaceship's body aren't the same shade.
Last but not least, I had to cut some pipes (and the like) because they weren't the right length.
Overall, it was a fucking nightmare building this spaceship. I don't think I'll ever buy a MOC again, and luckily, this was the only one I was interested in.
The only positive note is the price. The best on the web. There are almost 10,000 pieces, and if you buy the original ones, it would cost you over €1,000, but if I'd known about all these problems, I don't think I would have bought it.