Pros
Booz Allen is a great place to work because there is plenty of opportunity to network which helps with job stability. If you network with others and they are aware of your skills and work ethic, you do not have a problem finding the next assignment. Another great reason to work at Booz Allen is the annual contribution to the 401K. I is not guaranteed that the firm will contribute to your 401K near the end of the fiscal but the firm has contributed every year so there is a good track record. It is also one of the reasons most people stay for long periods of time so it is important to the future of the firm. The leadership makes sound decisions and is very competent. This is the reason I joined Booz Allen in the first place. I was very impressed when I interviewed and realized that the managers actually understood the work which was done by their direct reports. The managers of my previous employer did not seem to have a clue or care about how direct reports did their job.
Cons
Booz Allen is a great place to work but like all things in life, you need to be in the right place at the right time to have the opportunity to get to the top. This is the only frustration I have had with my time in the firm. I have been a developer and love doing development work however you will not get far in the firm if you are a technical person. When I say technical person I mean someone who actually writes code or configures network equipment. (If you are technical but only write policies and processes or manage technical projects then you can go far.) Sadly I do very little coding now but I am doing work which is more in line with what the rest of the firm does and should help me get in the right place to move upward in the firm. The bottom line is if you are hardcore technical then don't expect to move past the Associate level unless you are willing to take on softer skills.