Quick summary:

-Doesn't teach well...the book, homework, and TA will probably teach you better. He lays down the calculus fundamentals and the proofs for anything, but doesn't give too many examples.
-Super nice, and his class is super fun/funny. Always funny examples and demonstrations during class.
-Midterms are straightforward with no conceptual problems at all. Easy 100 possibilities.
-Final is impossible...very conceptual, not much number use at all on some problems. The average is going to be around a 40 according to him for the final.

I would recommend taking him. Oh wait but you can't since he is retiring lol. Although he doesn't teach well, you can easily read the book and learn for yourself. The book is presented very well, and 6A concepts aren't abstract, so understanding them should be fine. Although the final was hard, we will get a fat curve on it. Plus I think he curves each test individually, meaning we benefit even more than a total curve at the end of the class (since everyone has a 100 on lab and homework).

Very great professor. This is the first time I actually wanted to post a comment on a professor, and I believe Prof. Buchanan deserves it. 6A is the easiest out of all the physics series for LS majors, and Prof. Buchanan made it that much mmore enjoyable. Although his class is somewhat boring at times, overall, you learn a lot if you put a lot of effort into it. I didn't really study for most of the tests, but I got an A on one midterm and a B on the other. I should have taken advantage of how much he relaly wanted to interact with the students. He's very nice and willing to really help you out with your homework if you just take the time to talk to him during his OH (which he has like everyday). He's very funny old man, easily likeable, and seems like he really cares about your learning. TAKE HIM FOR PHYSICS. You'll do well if you understand the hw. His lectures go off tangent a bit, but you'll still get it. GREAT CLASS AND GREAT PROFESSOR!