wtf is this, why do we have to derive the formula for the probability of a molecule having a certain speed in the second chem class here? its harder calculus than 31A/B

TL;DR: He is not excellent, but definitely not that bad. 7/10.
My friends and I agreed that he is a sociopath, but that's not necessarily a bad thing. If you are fine with a professor with "I don't care" written on his face, you will find him a fairly good lecturer. His class is really engaging and as opposed to what most comments say, he never makes fun of the students' mistakes. He does not require a textbook because he writes a 500-page-long class note and keeps updating it.
The first two weeks are difficult but after that, it's mostly AP chemistry content. The homework is constantly hard, but if you frequently visit your TA (thank you Rupert!), you can get most points out of it. Even if you don't, the homework does not take many points anyway.
His exams are much easier than the homework and practice problems from discussion sessions and they are curved. There's no reason to blame the exam as hard since the average for homework is over 90% of the total.
And I think he looks like Eminem, which my friends don't agree.

The average for the first midterm was a 38%... enough said

Prof Bouchard is misunderstood by the student, I'd suppose. Even though the course materials are hard, Bouchard gives fairly clear lecture about these course materials. His lecture notes posted online are very thorough. The test is very hard, but if you work through lecture notes and the problem sets posted, you will be fine. Also, prof Bouchard is really helpful and really willing to help students during his office hours, and especially outside OH. He would simply tell you to just come by his office, and he will help you with your problems. Good professor overall. But if you simply don't like Chem 20B materials, you can find other easier professors.

The only class I've had that's miserable enough to warrant a review.

...The curve was incredibly lenient, though.

We only had two easy homework assignments the entire quarter (probably cause he didn't care enough, but hey I'm not complaining). Labs were done in pairs. We were given two weeks to complete a lab but running the actual experiment usually only took a day. Analysis for some labs was impossible without help from the TAs, but all in all, it was alright. If this is the only chemistry class you need, like it was for me, it was definitely manageable. But yeah, the class is designed poorly, to say the least.

Tbh, I liked the professor, along with many of my peers. That's probably because we had several classmates that were on par with class materials and engaged a lot with the professor during lectures. He was also pretty cool during the final presentation.

He teaches the hardest class I've ever taken, but also the best class. The material he teaches is well above the standard general chemistry level (more on the order of graduate level), but he makes it all very understandable. Furthermore, he writes you a fantastic textbook of lecture notes (and does NOT charge you for it).
Perhaps the best thing about his class is his teaching style, there are no hand-wavey explanations. Everything is derived, so it makes sense.
He is very nice in office hours and answers all questions very fully.

tl;dr: if you can put in a lot of work it's the best class available.

Avoid him by all means.

The worst professor at UCLA. Avoid him all you can.

Bouchard's lectures involve mostly derivations. He won't actually show you how to use the equations that he derives, nor will he explain any big conceptual ideas in chemistry/how to approach problems. You'll have to teach yourself most of the material. The only reason I did well in this class was because I had a helpful TA. Avoid this class if you can, or if you must take it, good luck.