I don't know why no one has written a review for Yarnall since 2004, but he's absolutely boss. He's incredibly wise and very kind, and his lectures are totally engaging. He is perhaps the calmest person I've met, but also really funny and great to talk with. I can't say enough about what an awesome man he is, and he really bonded with the whole class as did the students with each other by the end of the semester.
The class is not easy by any means, but it's a real pleasure and ultimately so rewarding to take. He runs the class as a cross between a lecture and discussion and there were something like 25-30 people, though it was a little awkward because we were in a lecture room twisting around constantly to hear people's comments in between his lecturing (though he said at the beginning of the semester he tried to get a discussion type classroom but couldn't so maybe this won't be an issue in the future). Prof. Yarnall expects a lot from his students, assigning like 200 pages of really dense reading per week fairly often and thorough courseworks postings on it. The upside is that you don't really have any grades until the final paper, which is a research paper on a topic of your choice within the topic. He stresses the courseworks deadlines and the no absence policy a lot in class, but I got the sense sometimes that if you're producing good work and not missing class too, too much he's not as strict as he seems. You have to go to class everyday as there's a sign in sheet that he will actually email you if you're not signed into for a day without an excuse.
Yarnall also stresses at the beginning of the semester that its good to have had a class in Buddhism before, and I highly suggest taking his advice. There were a couple really good students in the class who hadn't studied buddhism before, but the beginning of the semester will be tough because he teaches you essentially everything Indo-Tibetan buddhism teaches except in 2 weeks instead of a whole semester, and then gets much, much more in depth. That being said, I found this class ten times more interesting and rewarding than indo-tibetan, and while Thurman is a funny man, Yarnall is far clearer and more precise in his lectures, and very engaging. I felt like I came out of Buddhist ethics with a ten times better understanding of Buddhism.
The topic of ethics can get a little frustrating sometimes when Yarnall starts talking about some of the awesome metaphysical side of Buddhism but we can't spend more than one class on it because we're supposed to be focusing on the ethical side of Buddhism. The trajectory of the class after the first two or three weeks is pretty open-ended and Prof. Yarnall lets the students kind of pick what discussion/lecture is about, writing all of our questions from the end of the previous class on the board at the beginning of class and picking his way through them at whatever rate they take to answer. Sometimes a single question or topic would take up an entire class, other times he'd have a set topic to lecture on to steer us back on course, but he's open to everything which makes the class really interesting. He seems to know pretty much everything there is to know about buddhism, but he seemed just as interested and engaged in the ethical (and otherwise) debates the students had in class.
All in all, take this class or another class with Yarnall. He seriously inspired me on a daily basis, and even though it can be tough to keep up with the reading, you will come out of the class with an incredible new body of knowledge you won't soon forget.