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.

If you aren’t religious, you better start praying once you enroll in Bouchard’s class. The previous reviews hit the nail on the head. This class right here will be your most miserable in your entire undergrad. The lectures and labs are not connected at all, in lecture you will cover in depth statistics concepts that will leave you lost. In lab, you basically get assigned 4 experiments with no context given whatsoever. They did oral quizzes to make sure you were good with the theory before you could even enter lab. So they don’t teach you these experiments in lecture, but expect you to know it in lab. These experiments range from being 20 page protocols of some high level physics grad school shit that will leave you lost, to experiments that actually aren’t so bad but only one piece of paper given with no information on how to do data analysis or understand the theory behind the experiment, so you basically have to pray you can figure this out on your own. All figures have to be done using MATLAB, which they also expect you to teach yourself. The labs themselves, you’ll be standing there for 4-8 hours a week, lost and confused cause the equipment is from the 1990s or early 2000s and will most likely break down and give you shit data. You have to do error analysis and propogation on your lab reports, which also isn’t taught in lecture. To top it off, these lab reports are graded on the expectation that you write a paper at a PhD publication level (literally quoting the TA here). You won’t get your lab report grades back till weeks after the deadline, so you won’t even know how you’re doing in the class, and when you do get your lab report grade back, it’ll most likely be in the 20-40% range. The homeworks Bouchard gives are also completely long and unreasonable, when you also have these lab reports to write. You will feel like there’s never enough time to get everything done and you will be lost on every assignment. You will be stressing the entire quarter. Bouchard himself doesn’t give a fuck at all, don’t even try to go to him for help.

All that being said, try your best to get started on everything early, and if you’re completely stuck, go to your TAs for help, and show them that you’re trying your best and struggling. For the homeworks, even if you can’t do all the problems, just do something to get credit. You will definitely get some extremely low scores on multiple assignments, but it seems the curving is done pretty leniently. I myself bombed the midterm and one of the labs, and had no idea how to do some of the homeworks, and I got an A in the class. This will just be something you have to put 150% effort into and not overthink the terrible raw scores/not knowing anything and get through.

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.