Professor Halpern-Leistner is a very enthusiastic and knowledgeable lecturer, you can easily see how much he enjoys the subject matter, but his class was very demanding. Week to week, the WebAssign homework, for me, averaged about 2-3 hours to complete. The written homework was more difficult. On average, I spent 5-6 hours working through the written homework problems.The third homework assignment took me 15 hours to complete (combined), but, after realizing how long it took for everyone else, he adjusted the difficulty. If you do not dedicate the time to master the subject material in his class, you will, more likely than not, struggle on the quizzes and exams. I am an Economics major, and as much as I enjoy learning calculus, this course may be better suited for math majors. Professor HL was very active on Piazza, answering questions and clarifying subjects, but he prefers to "push" students to figure things out on their own, as opposed to just clarifying a lack of understanding. I cannot attest to his office hours, but given his enthusiasm, I assume he was more than eager to aid students.