Berkeley is what you make of it. I’m a first year humanities student and I haven’t found it overwhelming, but know lots of people that have. The difference between Cal and a LAC is they will not hold your hand at Cal. You can have great access to professors, most of which are top in the field, but you have to put in the effort by going to office hours, talking to them after class, and actively participating in class. As far as class size, it varies dramatically class to class and major to major. Assume that most of your intro classes will be large and with upper division class size greatly reduced. There are opportunities for small classes in your first two years though (I’ve taken 2 semesters of Spanish with less than 20 people and 2 freshman seminars each with 15 people). All lecture classes have discussion sections led by Grad students that tend to have between 20-30 people in them. Like with getting to know your professors, it is on you to get involved on campus. I too came from a big high school so this wasn’t a problem and I love everything I’ve gotten involved with. A lot of the social scene comes from clubs. I turned down many LAC to come to Cal and am very glad that I did. While Berkeley is a perfect fit for me, I would not recommend it to people that lack self direction.