Pros
The small size of the university makes it a pretty cozy work environment. Because the university has typically has large scale resources, there are lots of perks that go with being an employee here. Plenty of office and department parties, seminars, events that come with free meals. The campus is beautiful and easy to get things done because there are not a lot of barriers to access the most Senior management people. There are many events open to entire community. Cultural programming at Beckman auditorium, educational lectures by some of the world's greatest scientists, and musical programs give the campus a decent cultural life despite its small size and isolation from other universities. Case in point: the Caltech Olive Festival. Nowhere else would this have happened.
Cons
Being a small university is both a curse and a blessing. Many people within the administration were used to doing things in a unstructured, less-professional way because it is a small university and there are a smaller number of people to serve. Large turnover, "changing of the guard", and restructuring has occurred at Caltech in the administration over the last 5 years and the downsides are getting better, but remnants of the past are still there.