@harry: There was a slight adjustment when I got here. There is a lot more reading involved at the Upper-Division level (think about 1-200 pages per class/per week). The first
précis I turned in on a weekly reading came back with a grade of 7/10. I had been used to getting all A's with very little work or thought... that changed quickly. I adapted to the new workload and now it's not bad at all.
Also, be prepared for a lot of writing as well. I'm finishing a 20-page paper for a seminar class which is due next Friday and I just turned in the draft of my senior honors thesis last week which was 54-pages. Not all classes require papers of this length, but you have to do at least one seminar class and every history major has to write an honors thesis to graduate here at Cal.
With that said... it's really not that scary, it just takes some getting used to when you come from the cc level. But it's absolutely doable.