His lectures are disorganized and it seems that he doesn't go over the examples presented in class before coming to the lecture. I hope he will prepare what examples he is going to present in his class.

Compared to the couple midterms, the final was extremely hard (the average was 69 and only 2 out of 70 got higher than 90~) but he didn't curve that much. I ended up getting a B+ and people barely get an A in this class.

BE AWARE that STATS 100B class itself is fairly difficult regardless of the professor who teaches. It is a theoretical basis for subsequent upper-div classes thus important to know the ideas and concepts from this class.

This professor is pretty disorganized. His lecture notes were full of errors, and poorly structured. It was always a hassle to wait for him to upload the corrected version of the lecture notes on CCLE. Nothing is really explained clearly in these notes anyways, so you will likely end up spending the entire quarter teaching the class to yourself using the textbook and internet resources.
Pray that you get a good TA for this class too. My TA, Dong, was the real MVP of this course. He was very helpful, always uploaded homework solutions, and even gave a midterm review session with tons of hints on the exam.

Fortunately, his homeworks (6 assignments in total) and the midterm were very reasonable, as he is very computation-focused and did not drown us in proofs. Since this quarter was affected by the coronavirus, he made the final optional, which was very kind because the virus pretty much turned everyone's lives upside down and the stress made it hard to concentrate. He was also very lenient in terms of grading:
If you opt out of the final, your final exam grade will just be your midterm score.
If you do take the final, it is open notes, and your final exam grade will be the higher of your midterm score and final exam score.

The overall grading scheme of the class was:
20% Homework (6 assignments)
35% Midterm Exam (median score was a 86/103)
45% Final Exam

Bottom-line: Obviously, Christou is exponentially harder/higher workload than Li but truly cares A LOT about his students and rarely fails anyone, so you will probably learn more in his class. However, if you cannot take Christou for whatever reason, then Li's class will be a bit of nuisance at times, but ultimately, you'll be fine.

The lectures in this class were not helpful whatsoever. Professor Li had pre-typed slides that often had typos or mistakes, and even before tests, the answers to practice problems would be pre-written. Personally, I would have learned the material much better if he had done some examples in real time so I clearly knew the steps taken. The homework was very easy because the TA basically gives you every answer. Additionally, the tests ended up being almost exactly like the practice problems, so those were easy, too; I just feel like I didn't learn very much.

If you want to learn anything I would not take this professor. You'll most likely pass but you won't learn anything.

Professor Li is by far one of the worst professors I have had at UCLA. His lectures are incredibly disorganized and usually contain a lot of errors that are rarely corrected. That being said, if you want an easy A in an upper-div stats class, I would definitely recommend this class. The homework assignments make up 35% of the grade (there are 7 assignments in total), and the TA provides detailed answers to all of the questions during discussion. The tests are super straightforward if you study the definitions provided in lecture and look over the review problems given during the final lecture before the test. I had no idea what was going on in the days leading up to each test and still managed to get A's on all three of them.

Not good at teaching, but tests are very straight-forward. The TA this quarter is GOATED and helped us a lot with the hw. Would recommend if you care more about your grade than learning (or you can also just self-study). However, if you want to learn I would recommend someone else.