Pros
MITRE's mission remains important as a glue for the federal government and accelerator for its needs without just thinking of its bottle line. Your work life balance can be pleasant, and there exists stability depending on which division you are in.
Cons
MITRE is at a deceaive poont in what it wants/needs to be. It is struggling to compete with industry salaries, is in an increasingly hostile environment for its mission, and believes the solution is to be leaner and become a standard contractor. This isnt the answer. The whittling down of benefits with lower pay doesn't bode well for long term employment as increasingly the culture of working in the public interest is playing second fiddle to making money. Staff with strong skills still exist but are spread thinner thanks to the past few years' policies. Hiring is increasing for people earlier in their career, but if adequate time isn't invested to transfer knowledge, MITRE is likely to see heavy turnover in the absence of strong protections for employees, commitment to education, and commitment to its core mission. Your ability to do your job has little to do with getting promoted.