Pros
Fresh grads and smart scientists/engineers/programmers who come with tons of enthusiasm and are very smart. A great past legacy that needs to continue.
Cons
Right now, this is a good place for managers/VPs/CEOs with PowerPoint skills rather than worker bees who are passionate about math, science and engineering. MITRE has a high overhead because of multiple layers of management who do not do the actual technical work. If you are a dedicated technical engineer, you will barely see a salary raise. Overtime, this may lead to doing "just enough" to survive or leaving for greener pasture. Because of the high overhead, you could be overloaded with a task (when or if it becomes available), since the layers of managements has to get their cut. A task that should be done fundamentally by two or three engineers is performed by one engineer/scientist. The engineers and scientists don't get recognized for their contributions. This is probably one of the causes for the higher attrition rate. The demand for quick results -- which can lead to low quality work --, and not training engineers, is also a big negative. MITRE wants to publish more quality research, but they do not provide funding or necessary time to do so (overhead issues). Lack of investment in fundamental sciences (Physics, Math) and engineering. Too much focus on the AI hype. Some upper managers seem insecure if engineers want to directly correspond with sponsors. Reward is heavily skewed towards managers with DoD connections who often lack real technical skills.