Pros
Investigators are leaders in their fields of study and if one can afford the low pay as a sacrifice in order to work there, all will be fine. UCSF does have an extensive program to help post-docs transition to independent positions after completing their fellowship - this program needs to used by more post-docs as it represents an excellent recourse. Very wealthy research institute, well equipped with the latest instrumentation, and facilities are pleasant to work in - modern. Lots of community efforts to have post-docs socialize and exchange ideas in order to promote collaborations for now and in the future.
Cons
Work like a slave, no security, low salary in a very expensive city. If an international post-doc, UCSF uses Visa status as a means to take advantage of employees - i.e. threatening cancellation of Visa consistently. Very little room for promotion, MD's valued far and above Ph. D's, benefits for post-docs could be much better, especially vision and dental.