I have talked to numerous people, both alumni and current students of UoP, and they all tell me that the 1st year is hell, but the 2nd and 3rd are not too bad. I was told that I just need to survive the 1st year.
Since I have already taken a ton of upper level bio classes, I hope that will help me keep up with the pack.
Basically, UoP can finish in 3 years because on years 2 & 3, classes start at 8 AM, and evening clinics run from 6-9 in the evening.
Yes, I am expecting the curriculum at UoP to be completely overwhelming and challenging, but that is the case at any d-school.