The classes range in various levels of difficulty. It really depends on the class, professor, structure, and department. From my experiences, English 305 and Geology 101 are the toughest classes I've taken. I ended up dropping both these classes, because I could barely pass them. Some people managed to make at least Cs and pass, while others floundered through them and had to repeat them. I had to take English 305 synthesis course to continue as an English major. Sadly, this didn't work out, so I switched from English and now major in Communications. The history classes for the most part aren't too bad. It really depends on the professor, so read the reviews and pick a good one. Generally, the professors in the history department are really good. I particularly enjoyed taking History 352- The South After Reconstruction. The writing in the classes are more based on content and clarity. As for Communication classes, some professors are good and some are bad. Try to take the really important classes in the fall, because the really bad professors teach in the spring. As for other departments, I have heard the Math, Science, and Engineering courses are challenging. Also, some theatre classes can be time consuming, so be sure they fit in with other classes. The English classes at George Mason are ridiculously difficult, so the English department has more English minors than majors. The English 305 class does a brilliant job of weeding people out of the major. In the end, mostly the emo and overtly unconventional personalities remain. Still, I don't see George Mason's English department on the top 10 of any rankings. If this were the case, then it would be a different story.
As a music major my classes are generally smaller then the average college class, especially once you get to the upper level classes. It wasn't until last semester that I had a class with 100 students in it and it was a class for my history major. However, not one class had all 100 students there. I like the variety of classes offered for my history major and the variety of professor who have different strengths in different fields of history. For my music major the professors are more set in stone, but this is because my music degree is preparing me for a very specifc job, while history is more broad in the career oppurtunities. There are a variety of class types, lectures, labs, discussion, and research based classes. The key is to try and take classes that play to your strength and when you have a class that isn't set up to your strength that you talk to the professor and/or TA. Get help early if you need it to succeed. Professors want you to learn, so generally they are more then willing to help a student who asks.