I took a major requirement at UCB last summer. I can attest to the difficulty, but classes are structured differently than CC classes. Lecture and discussion are made separate (lectures are given in relatively large lecture halls by the professor, and discussion sections are held by graduate student instructors in smaller groups). I found this much better for learning in general.
Classes are generally 3 units at CC, while they are 4 units at UC’s (because of the extra discussion section). As such, you will be required to do more work, and classes cover slightly more material (and are a bit more intense).
IMO, you will be less coddled at a UC than you are at a CC. You will not have multiple choice tests, and you will have to know the material thoroughly to do well on exams.
Depends on the major, though. I hear that UCB’s CS classes are notoriously difficult, I don’t think much can prepare you for that.