Overall decent professor with straightforward lecture. Fairly interesting. A lot of the grade is based on homework though, so that's a plus. Half of it is from the online course work, which is actually quite helpful and you should have no problem getting full score there. Written homework is graded based on completeness and correctness; basically TA checks if you did all the problems and check one problem for correctness. Not too difficult, just got to be careful.

Things to note. Only one midterm, although unlike his previous quarters, this time the midterm was kinda hard and the final was pretty straightforward. He allows one page of notes on midterm and two on the final, so make sure you got all the equations and concepts. He did spam a lot of information at us in the last 3 weeks, so yeah.

Mason is a nice professor. Recommended

At first I really liked Mason and thought that he was a pretty good professor. The midterm was easy (I got an A+) and the homework wasn't too bad either. Because of the ridiculously hard final (average was a 64% and he didn't curve the final or the class), my final grade went from an A+ to a C. I was shocked and, after a year, am still bitter about it. Overall, decent professor.

I had Mason for Chem 20B Winter 11 and he was a great teacher. There's only 1 midterm, and the homework is completion credit and a grade booster. His midterm was quite similar to his last midterm, so I got an A+ on that. He allows 1 page of notes on the midterm and 2 on the final, but he doesn't check... The final however was very hard and I spent the whole 3 hours doing it. I ended up dropping from an A+ to a B+, but I heard that the average on the final was a D.

After failing Felker's 20B class in Winter of 07, I had to take this guy's class in Spring 08. And boy, this was a complete cakewalk. You may think, "Well of course it's easy, you took the course before." True, but I did not learn anything from Felker as he did not assign any graded homework. I did not study extra hard for Mason's course even though I should have (it would suck if I didn't do well the second time). Yet his class lectures were extremely reasonably-paced and he explained the material crystal clear. The notes I took from Mason were so much easier to understand than Felker, so it was pretty much guaranteed that I would pass this course with no problem.
Mason is a bit too easy, per se. 30% homework? I don't think any other professor in all of the university is that generous (Besides Computer Science projects). Half of the homework is online through OWL (similar to MasteringPhysics except it's not a waste of time like MP is). OWL is a useful tool for the class, not a distraction or time-waster. You can try each problem as many times as you want until you get it right, and it will never dock any points. So that 15% of your grade right there, at the cost of 1~2 hours a week. Now sometimes a problem is really tricky or long, but you can just skip it. Why? Because you only need 90% total on OWL to get the full 15%. Basically, an 9/10 overall on OWL is still a 10/10. For me, this didn't even affect anything, as OWL was easy for me to do since Mason's notes were awesome. It blows my mind that he make everything so easy. The other 15% of the grade is written homework, much like any other course. It's not too bad, he assigns fair problems and drops the lowest score like any other prof. There is only one Midterm in his class, which could either play to your advantage or disadvantage. For me, having one midterm is much easier, and I did really well on it and it pretty much secured me an A for the class. The midterm is another 30% of your grade, and the final is 40%. Both his tests are very easy and it wouldn't have mattered to me if they were worth more.
Unfortunately, I could not attend his office hours since they conflicted with my schedule, so I have no clue how much he cares about his students outside of class.
But all in all, if you want an easy 20B course, take Mason.
P.S. I got a C- in 20A, and I still managed to get an A in 20B with Mason. Eh?

I'm not sure why this professor's ratings are so low. I thought this class was very fair. It seemed like there was a TON of homework, but that's probably because I never did bookwork in Scerri's 20A class (I know, it's lame, but I didn't see the point, partially because the t.a. never went over it).
That being said, homework was 30% of the grade. THIRTY PERCENT!!!!! So, that's basically 30% in the bag. Additionally, I found my t.a. very helpful.

His lectures were a bit slow, but he managed to cover everything and I found the pace somewhat refreshing after being so rushed in LS last quarter. Also, he wrote a lot of what he said on the chalkboard, so unless they were unconscious, everyone in the class had ample time to take notes.
I didn't quite have enough time on the midterm (one of the later questions threw me), but there is no way that you could run out of time on the final.
Very fair class. Take it!