100% agree with review below. At least Christou cares (a ton) about you, your well-being, and your learning. Xu is more or less a robot-- very cold, callous, and unhelpful. Really difficult curriculum like Christou-- difference is Xu's heartless while Christou has a massive heart

Hongquan Xu is by far one of the worst professors I have ever had. Here's a breakdown of everything awful about him:

1. One of the few upper division stats professors that requires you to purchase a textbook
2. Has an accent that makes him unclear
3. Bad speaker
4. Does not answer questions in class well
5. Difficult to get his attention in class since he just mindlessly copies down his notes onto the blackboard as he lectures
6. His curriculum is basically ripped off of Christou's, from his material to the homework (screams lazy, and that material is hard)
7. Not helpful in office hours
8. Does not care about students' learning
9. Terrible grader, offers little to no partial credit on math problems
10. Goes really fast in his lectures, and no podcasts
11. If your notes involve just copying down everything he writes on the blackboard, it won't be enough.

I bought the textbook, read it thoroughly, attended every class, did decently on the first two midterms, and did pretty badly on the final. His grading policy to not offer partial credit destroyed my grade despite doing well on the midterms and the homeworks. He's not just an awful professor, but he's also not very nice or respectable. Don't take him if there are other options.