The review right below is very comprehensive. Sums up everything I had in mind.

tl;dr Avoid taking her, there are many many much better physics professors than Ni Ni

My first quarter experience at UCLA was totally haunted by Prof. Ni. She has a think accent but to her credit she tried really hard.

After midterm1, I decided to quit her lectures and study from the textbook instead, just like everybody else.

I'm still trying to figure out how she got the job.

If you can avoid taking her, do! Her lectures are poorly organized and she mostly just reads from the textbook. She also has a relatively strong accent and doesn't project very much, so it's hard to hear/understand her. Her midterms were okay, but she misspells a lot and the TA's had to clarify and actual changes parts of problems so they made sense.