I train in a Crossfit gym, although don’t really do CF workouts.
It gets a lot of stick for no real reason as far as I can see. Like all gyms, some have good instructors and some have bad. You’ll see more bad form in chain gyms where 99% train unsupervised.
In the box I go to, if anyone is showing bad form, someone stops them and points it out, even if you’re not in a class and just training solo.
Most of the high intensity / high rep stuff is done with light weights (relative to 1 RM for that person), so even if form does dip a bit at the end of a set, the risk of injury is very low as the weight is relatively light for that person.
Personally I’ve enjoyed it, I’ve learnt quite a few new skills and improved technique on my Olympic lifts.
A typical class would be 5 min warm up, 20 min skill session, tightly supervised, honing good form, then either one or two blocks of activity, which will vary depending on the class, then a 5 min warm down at the end. Strength classes would have a weight lifting based activity e.g. 15 mins to establish technical 3 rep max Deadlift, then 15 mins to establish 1RM Clean and Jerk. ‘Crossfit’ classes would be more a circuit style thing. All the classes are part of a programme which runs in a cycle aimed at developing a skill / strength in 8/10 week blocks, so if you do the same class each week you should improve in that skill set. Everything is measured once every block to gauge progress for each participant.