Okay, based on just coming out of her LS 3 class, she is a decent professor. She's not amazing and engaging, but she's definitely not bad either. Her lectures are all on powerpoint, and you are only responsible with what she goes over on the slides in class, not what is in the textbook. Oh and don't buy the textbook. It was a waste of money, I barely touched it. Honestly, if you don't understand a concept, the internet is way more helpful. There's tons of video modules that explain things better on sites like McGraw Hill.
Her lectures are boring, yes this is true. Every class she goes over a new slideshow. But they're manageable. And she's a nice person, so if you don't understand something in lecture, just raise your hand and ask her. Tons of people did that this past quarter. Her office hours definitely helped too. Just about every lecture I would walk out of class with retaining less than half of what she covered, since she went kind of fast. But thank goodness for for bruincast. Rewatching ALL the videocasted lectures helped SO much with understanding everything she was saying and taking good notes.
If you're like me and think that this class has a lot material, then study consistently for it throughout the whole quarter. This class is manageable as long as you give it the time it deserves, which is a good amount of time. I think LS 3 is harder than LS 2 because unlike LS 2, which is pretty much straight up memorization, in LS 3 there a lot of concepts having to do with experiments that you need to grasp, because on the exams she'll ask you things that you may have not seen before but you'll be able to answer them if you understand the concepts behind the class. But there is still a lot of material that is straight up memorization from the lecture slides.
Johnson's curve is more generous than I thought. I did well on the first midterm, got a little below average on the second midterm, and did well on the final, and ended up with an A+. After I calculated my raw score, I barely had a 90%, so go figure.
My advice would be to treat this class like it's really hard, and you'll do fine.
Overall, I'd say Johnson is very nice and helpful, but fairly boring in lecture. Make sure you get a good TA that can explain things well, or switch into a discussion that has a good TA. Discussion is mandatory so you might as well go to one that is actually helpful. Also, you should sign up for PLF at Covel, it keeps you on top of things.
As others have said, this class is manageable, but put a good amount of time into it.

Okay. To start this review, I must say something. I don't normally write reviews for professors. With that said, I am absolutely in love with Dr. Johnson, and I am excited to write a humble review for this amazing professor. She was THE MOST amazing professor that I've ever had the pleasure of learning under at UCLA, and every day in class was an enlightening, enthralling experience. Having not taken AP biology in high school, I was a bit worried coming into the class, thinking that I was underprepared. Indeed, the first few weeks were a struggle, especially when doing the clicker questions. However, you'll see why she's such an effective lecturer in about the 3rd or 4th week. All the nuanced points she made in earlier lectures cycle back, and all the concepts that you thought were meaningless detail are breathed life. That protein whose name seems really obscure and unimportant? You'll actually learn ALL about the structure and function about that protein, while also learning about the chemical pathways and interactions it has within the body! No small figure in a lecture slide is "meaningless"- in fact, EVERYTHING comes back to a full circle, and the topics are arranged in a brilliant way that makes one really appreciate the scope of Dr. Johnson's ingenuity and brilliance in pedagogy. Dr. Johnson is very engaging, and also very, very kind. Going to class everyday was like going on an adventure, and just like any good adventure, make sure to prepare well!

I remember one of my favorite lectures from this quarter, which was her lecture on DNA replication. When the topic first came up in LS2, I was utterly confused and lost. I didn't know what the difference was between a chromosome and a chromatid, and there was no real intuition behind the processes that allowed our DNA to replicate. I knew all about the semi-conservative model, but WHY is it that way, and WHAT about molecular interactions make it that way? Dr. Johnson's lectures answers ALL of these questions, and quite deviant from other lecturers, she actually chooses to teach about RNA transcription and protein translation before DNA replication, which was an ABSOLUTELY brilliant choice- learning about these topics first made DNA synthesis not only intuitive, but VERY simple. These topics cycle in such a way that makes these very, very difficult topics (topics that people struggle with all the time in the MCAT) so simple and intuitive. I wished that she would teach more classes, and I think you can tell by this post how appreciative I am of her class. Thank you professor Johnson, and happy holidays!