Fall 2019 - I liked her! She's a standard good math professor - gives good examples to understand the concepts during class, gives good practice questions for homework and doing them all myself (even if it took like an entire day sometimes) really drove the math into my brain, which is basically how math works anyway. Her midterms aren't great because she gives you 10 extra credit points that just makes the paper unnecessarily long and that makes it harder to just get through the paper. But I think that's mostly because it takes place during the 50 minute lecture time and you can more than make up for it in the final when it's a kinda-longish paper but you have three whole hours to work on it. This class is just practice a lot and you should be okay. She's a good professor! I think a lot of people rated her badly because they aren't able to deal with the material properly - which could be for many other reasons than the professor.
Fall 2021 - I found the material of this class to be very challenging. However, Prof Greenfeld's lectures are generally clear and you can tell she tries her best to make sure everyone understands the material. When many students (including me lol) performed poorly on the midterm, Prof Greenfeld made sure to slow down during lectures, check for student understanding more often during lectures, assign shorter homeworks, and modify the final so that at least 75% of it would be based entirely off class notes and homeworks (so basically exact problems and definitions that we had seen before). She told us of her plan for the final two or three weeks before the final, so we were given plenty of time to prepare. She also welcomes students at her office hours and has never made me feel dumb for asking dumb questions. I personally think that Prof Greenfeld's changes after the midterm helped me a lot in her class. Still, I had to put in a lot of work for this class (attending every single lecture, spending 7-8 hours on homework each week, and attending office hours whenever I had the chance) in order to get an A. This is definitely not a class to fall behind in!
Winter 2022 - Prof Greenfeld cancelled our midterms so we had no idea how her exams worked going into our final, and homeworks and final were graded incredibly harshly, forcing us to write out every step for basic integrals we know from 31b or proving results shown in discussion. Do not take this class unless you want to spend 11 hours on a final exam and have it nitpicked till there is nothing left.
Spring 2021 - As a double major senior student in ECE and Applied math department, I have took more than 30 upper div classes in UCLA and I never felt this lost in any of my coding, engineering or math classes. The professor doesn't know what she's talking about and I noticed she got all her notes and hw set from Professor Killip's fall quarter. Basically her lectures were the worst lectures I have attended (so I stopped going to live lectures after week 3 and read the book instead) and the test are ridiculously long, time consuming, and hard. My advise as a UCLA Alumni : AVOID HER AT ALL COST EVEN IF SHES TEACHING BASIC ALGEBRA