Pros
I don't know how helpful a review I can write, because there has been a round of layoffs and we can expect more in 2025, so I wouldn't pursue a career here right now unless you are recruited onto a specific project requiring your specific skills. I found the salary and benefits very satisfactory, although even before all the recent changes to the federal government, we were already feeling the weight of a changing economy.
Cons
I think the biggest con is that this was once an institution where one could establish a network and then expect some degree of job security. This is no longer the case and may not be for a long, long time. Also: Like every other company I've ever worked for, MITRE's commitment to diversity was never anything but window dressing. Like anyplace else you'll every work, white, straight, males will be promoted before anyone else; no one will ever, ever make a specific bigoted comment but the decisions will reflect bias. Efforts to address the issue are seemingly designed to be ineffective. People care hypothetically but there is no effective way to shift internal bias and no one is ready to try.