Pros
Some of the best reasons are the status of being associated with Princeton even as a mere employee, access to first-rate scholarly events and the library, a relaxed environment in relation to corporate employers, a feeling of belonging to a community.
Cons
The pay is generally low in proportion to corporate employment. While the faculty and students are not in general snobbish as some might expect them to be, the upper level administrators can be quite vicious towards the lower level employees. For example, if you write grammatically, they'll charge you with verbosity, because they believe that people from "inferior" schools cannot write at all. A small number of legacy students affiliated with the traditional "eating clubs" can be real jerks. Don't expect to be able to work and study at Princeton. The benefits are continually used as a cash cow by the administration. Despite its large endowment, the university is under some financial pressure owing to the stock market crash and may be expected to find ways to not meet promises. However, you do get TIAA-Cref and this is a first-rate pension plan.