Pros
Really depends on which department you work for. Some departments are very flexible and supportive, while others can be an absolute nightmare. Generally, people are friendly and bright. Great benefits. Tuition assistance is the most valuable perk, however not everyone are able to have the flexibility to work full-time and go to school.
Cons
Salaries are abominable, as well as very inequitable across departments--even within departments. Almost no opportunities for advancement aside from changing departments or leaving altogether. Staff are paid substantially lower than faculty, yet are always the ones to be passed over for raises, get more work dumped on them, etc. Can be a total bureaucracy. Some "lifers" are lazy but yet highly compensated, while those who work hard are not rewarded. There can be a real disconnect between the values claimed versus reality.
