I've graduated for more than 10 years from CAL and my undergrad years in chemical engineering department is the most grueling years in my life. There was very little camaraderie among students and between students and professors. The academic studies, while challenging, lacked meaning, as it was very detached from the day-to-day world. Some TAs and school administrators were jerks. Despite having no social life and feeling miserable all the time, I don't regret my experiences at CAL. I loved the fact that the program really emphasized lab work and writing lab reports. The experimental techniques I learned back then are still relevant today. It humbled me academically as I tried to survive in the pool of bright and hard-working souls. It also made me a better worker for life. The degree itself carries a lot of weight when you go look for a job, although it still took me a few months to find the first job. I would go to Berkeley again, given the chance, Don't expect to enjoy the experience, but you will look back with a lot more appreciation and insight.
The school is insanely difficult. This is not a problem because in some cases it is fairly difficult, however in some undergraduate prerequisite classes there is a swath of professors who are bad at teaching, while continuing to keep the course material difficult. Without prior background knowledge in these courses I find it hard pressed to survive and do well without spending a lot of time in them. This is not to say all the teachers are bad, it is just saying that a couple of awful professors have been ruining my overall learning experience.
I like CAL a lot more than I thought I would. The first week of school was a bit overwhelming. Now that I have figured out how to register for classes etc., I am really happy with university life here.