Pros
MITRE is a long-standing, strong institution. The company does good work and is staffed by great people. The work you do here cannot be done elsewhere.
Cons
MITRE, in my lived experience, is a "Culture of Genius". In cultures of genius the corporate focus is on wooing, retaining, and leaning on the contributions of star performers ... considered to be innately more capable than other staff. [Forbes] What this specific culture means in practice is that staff with strong technical skills and good interpersonal ability will find work and be rapidly promoted through the system in a fixed mindset culture, where management holds the belief some people were born with innate success competencies. In the meantime, average staff who work hard to hone their skills and improve themselves will not always be rewarded for striving to succeed; in fact, the perception of having to strive in a culture of genius can lead to negative reputational consequences. A culture of genius promotes inter-staff competition. This austere competition environment is detrimental to the health of the company, and has led to anxiety, uncertainty, and the atrophy of both 'genius' star performers and dependable staff. In a resource-constrained environment, protective circles of acquaintances form to provide mutual protection and stability (think Hunger Games, Game of Thrones). In the process, collaboration and innovation within MITRE sharply diminishes.