Pros
The best reason to work for MITRE is the opportunity to work on very interesting and important government issues. The work offers an inside view of government operations that few others have, including traditional consulting firms. The employees are well-educated and highly competent for the most part. The company encourages matrix management in order to get the right skills for each project and aims to highly collaborative in its approach. The company seems to truly encourage a work-life balance (in contrast to other organizations where management talks about balance but does everything in its power to discourage employees from pursuing any of the flexibilities offered). The retirement program is very good with generous matching and the funds are vested immediately. Vacation time is also generous--about 23 days of PTO per year. Staff can work at any time, at any location.
Cons
Unfortunately, of the all the talk of "working in the public interest" and offering objective opinions, MITRE staff are firmly in the pocket of agency management. There seems to be a genuine fear that failure to agree with agency managers will put the company's future in jeopardy. (And, admittedly, this may be true--however, honesty in the company's mission is desireable.) The organization is supposed to be flat and there appears to be little promotion opportunities for many people. (although I am told that annual increases are "generous") Many managers have gigantic egos and are unafraid of what they don't know. In addition, project management skills are lacking in many quarters. Upper management is invisible; the lack of a clearly articulated vision is extremely evident. The peer review process is a free-for-all which produces questionable benefits.