So I thought I should do my part as a Math major to tell y'all about Caputo, because I wasn't informed about him when I first came to UCLA.
I can tell that as a mathematician, he's very smart. He gives clear and good examples. His lectures are very thorough. The books he recommends are very advanced. He's made me more interested in Probability getting out of his class than when I first got in, and it's a shame that I didn't know him for 170A. (I had a horrible teacher for 170A and my knowledge was completely screwed up.) If you have him for Probability, I guarantee you'll have a more in depth understanding of the subject. Though I must warn you that he has a high expectation. His tests aren't so hard; they're all doable, I know that I screwed up in them because I'm not so smart when it comes to Probability. However, I still got an A, and it should show you how merciful he is.

Some people would feel a little uncomfortable around him, because frankly, he's easily irritated. Sometimes I also think that he's favoring some students more than the others. Just to warn some people who are super sensitive. But if you're like me, you'd only care about the material and how much you can get out of a professor, not his temper, you should definitely take him; he'll be around when you have questions.

Overall: if you want easy As ONLY, take Effros. If you want good grades (not easy As of course) and good knowledge, take Caputo. It's up to you.

I thought Professor Caputo was a good teacher overall. He really is knowledgeable--it's just that the subject is not that easy to grasp at first. I'm not sure if he's still continuing to teach at UCLA or if he's going back to Italy but if he does teach 3C again, I would definitely recommend him. The key to Caputo's style of teaching is to do the homework problems and not overthink the concepts. Probability is all logic but the concepts that try to explain it are sometimes confusing. His tests were not hard at all; the only reason you wouldn't do so well is because of overthinking. He and the TAs really are generous with partial credit and the final exam was not bad at all. Caputo doesn't give you more than you can take; my other friends in Professor Weisbart's class covered stuff we didn't even talk about. If you really do the homework problems on time and keep on practicing (homework is collected and graded but doesn't count towards the final grade), then you should be fine. Definitely take Caputo if he is still teaching.

Caputo wasn't a bad professor, but he wasn't great. I think that the subject material of the class is a little complicated at first anyway, so the slight language barrier isn't very helpful at first. However, he is very open to helping you out in office hours and will arrange to meet you at alternate times if you can't make his office hours times. His midterms and final are not difficult if you are comfortable with variations of the homework and example problems. The one issue that I had with Caputo was that he took absolutely everything (lectures and example problems) straight from the book, so when looking for other problems to practice or variations of certain problems, I was very much limited. Overall, Caputo wouldn't be my first choice (I've head that Wiesbart is amazing), but don't worry about trying to change classes if you get stuck with him - you will be fine.