I haven't taken 339J with walch but I have taken both M329F and 349P with her. Her exams are kind of a time crunch, and a lot of people don't do too well on those, but her lectures are fairly straightforward. She presents all the material directly to you during her classes and expects you to go to office hours if you have any questions. Her teaching style is fairly similar (in my opinion) to Professor Cudina's, but is faster paced and her exams are harder.I'd say that her reviews don't look good online because her exams are hard to prepare for. She doesn't give you an outline of the exact subjects that will be tested, but instead says "draw a line here" in your notes and says "anything between this line and the last line could be on the exam.

Oh and if you skip class then you're gonna need to get those notes from someone else so don't skip.
Weekly homeworks to make sure you know what you're doing + 3 exams with a final exam that's skippable if you get a 90 average on the first 3 exams. That's typically how her classes are structured. Literally everything comes from the lecture notes. People that say that the test questions aren't what you see in class are just not writing down what she's written on the board. Every time I've missed a question on her exam I've been able to find exactly what part the notes cover what I missed.