I agree with all of this. The Borg Cube especially was very difficult to assemble, and I've done some pretty big official Lego sets so I'm used to a good challenge. I had to resort to gluing some parts in place, as some of the plates were bent and just would not stay in place while I worked on the next side.
I also really came to dislike the tiny black pieces they use to add studs to the bottom of some bricks. Too small, too hard to insert, and way too easy to just roll away and never be found.
That said, the final product looks fine and nobody ever questions if they are legitimate sets or not. I don't regret the purchases, just didn't enjoy the build process like I normally do.