Prof Jin's course is of standard difficulty, or at least in terms of one of the most difficult and fast-pace courses here. His lecture notes are always fantastic and help you learn quantum. He might give difficult finals but he'll do curves. Sometimes his wording (in HW, lecture) is confusing, but you'll find it inspiring after getting his meaning.

Terrible professor. Told a whole class of physics majors that they arent trying hard enough rather than stopping to question the quality of his own teaching

Worst physics professor at UCSB by FAR!!! Super condescending and passive aggressive. News flash Mr. Chenhao if everyone does bad on your exam maybe you need to do a better job teaching instead of blaming your students. The exams are calculation heavy and don't give any physics insight; too many problems for midterm. The lecture are below subpar.

Everyone did bad on the midterm and he told everyone that they were not learning well enough.

Hes an okay lecturer, at least his notes are typed and readable. His exams are rather difficult and be prepared to read a lot to prep for exams.

His homework is difficult, but doable. They are all from the textbook's exercise or modified versions. The difficulty is not from the professor but quantum mechanics itself. There are unexpected questions in exam. You have to use your concepts creatively to solve it. You have to be good at math otherwise this course is a disaster.