Lecture material itself is boring, but I don't think any professor could make stat mech sound interesting unless the student is genuinely interested in the stuff. That aside, Mason's lectures are super clear and easy to take notes on. Basically copying them for word for word and writing down occasional comments from him will give you almost everything you need to do well on the exams. The rest you have to make up by reading the textbooks and doing homework. Also the grading the the exams are very generous; bunch of partial credits given. I recommend taking 110B with Mason.

TL;DR - Hard class, Professor Mason explains stuff well

This class was incredibly difficult. There was long homeworks due every week that took a lot of time, and the tests were very difficult, I'm also of the opinion that this has a lot of the conceptual/mathematical complexity of quantum mechanics without being quite as interesting.
As for Professor Mason, he isn't the most engaging lecturer and his voice can be monotone at times, but he explains the material very clearly and effectively, answers questions very well, and provides critical information very clearly in lecture. He was receptive to the class's needs, and readily dropped the Mastering Chemistry part of the course when we clarified that none of us already had accounts and also the software is terrible, and that was super awesome of him. He requires two textbooks for the class, and you will need both for the class.

At first he sounds boring--but no he is not.
He does not look approachable, but he is.
Class is rather easy and straight forward.
I'd like him to expand more on concept rather than giving plug and chug equations.
Notes are crystal clear -- you can follow what he's doing even when he's doing it in class.
Paces his lectures extremely well.