Okay, some details
I was a new diver (75 dives) taking GUE-F. The instructor recommended that I do the course in doubles (my first time ever in doubles). I did not receive any valuable criticism or feedback, only ridicule the entire course, from multiple GUE instructors who were present
The instructors repeatedly put me into very difficult situations and then they all laughed at me when I floundered, e.g., I never did a back kick before, and I was put facing down the current while doing air sharing drills. The instructors ridiculed me when I couldn't keep my position while back-kicking into a stiff current. I never received any instruction in the back kick during the entire course. They had video tape of me trying to back kick into a stiff current, and the instructors played the video in class in a loop over and over, laughing at me and making fun of me the whole time. The entire course was like that.
The instructor said that normally he gives out GUE course manuals, but he wasn't going to give them to us. He told us to find someone else who taken GUE-F and get the course materials from them. The instructors ridiculed me for not knowing things that were in the course syllabus that we never received.
I bought a custom DUI drysuit from the instructor during the course. It didn't quite fit correctly, but the instructor insisted that it was fine. Years later I found out that I had paid for a custom drysuit but the instructor had given me a stock drysuit and pocket the $800 difference.
I took my concerns to the top at GUE and got about the same response from GUE HQ as I did the instructors.