Hello!
I've just completed my MSc in Chemical Engineering, and I thought I could write you a few tips that I wish I had known. Regarding the professor ratings, it depends entirely on the university you're attending, a quick Google search will take you to a page where you can filter professors by university (the ones I have attended were not on this list). Speaking from my experience, the workload was heavy! It was not impossible though. Doing a research based degree and having course work made it quite tough to balance both. The one thing I would suggest is to develop a schedule for yourself and write down all your tasks and important deadlines. Ask questions when you don't understand something, engage in class, and finally enjoy the process. I did enjoy it but not as much as I wish I did. I sort of fell into a dark time because of a bad grade and I let it affect me way more than it should have. I ended up graduating with a 3.58, and a very strong thesis - the point is, sure grades are important but what distinguishes you the most is the quality and strength of the research you conduct.
I wish you the best of luck, and don't forget to enjoy it!