In terms of work load, it's not a huge step up from the 31/32/33 series. I would still say that 32B was harder than 115A. The professor is good, really nothing to complain about. His explanations were sometimes a bit unclear, but he encourages questions and will gladly clear anything up if you ask. I had a really good TA who helped alot, and most people went to the TA office hours, rather than the professor office hours. Regardless, the math class isn't particularly more difficult than any others, and at the very least, the professor doesn't make it any harder.

First of all, I took this class during COVID times. Second of all, to the person who said that 32B was harder than this class, jeez. Don't get me wrong, Professor Honda is a super nice guy. Probably one of the nicest professors you will ever have. He has this funny laugh that you will just know when you hear. But in terms of teaching, his lectures often weren't too engaging and sometimes it was hard to keep up since he was using slides. Hopefully he will choose to write more in the future. This was the first upper div math class I took, and it really sucks that I had to take it online. He assigns HW, but it isn't graded, so you don't really know if you are writing the proofs effectively. I'll just say it, I had a really rough time. None of the quizzes are dropped, and I failed a couple quizzes. I spent most of my Math 115A time in the TA's office hours. Hopefully your TA will be Eilon, he is a gift sent from heaven. He was always willing to help and was super clear about concepts. So with that being said, make sure you attend discussion. Manage your time on the exams, and don't slack off with the HW just because it isn't graded. Stay on top of things, and if you fail the first quiz, seek help right away and don't just assume it was a blunder on your part. I forgot to mention that the curve was very generous, so that is indeed a plus.

You should take professor Honda's 115A.

Professor Honda is really nice. Math 115A is a hard class but he tried to make it easier. He gives out sample exams before midterms and finals. If you study through the samples and go to his and TA's office hours, you will know how to answer the exams.
You do not need to submit the homework but it helps you with the weekly quizzes.