Pros
Booz Allen has an excellent reputation in the government contracting business and they have a presence in nearly every government agency and organization. If you are in the DC Metro area and are looking to get a stronger network presence, Booz Allen is excellent for creating such.
Cons
The corporate culture is focused on directing people to become project managers, department managers, etc. The forced process guarantees that you can only get promotions and raises if you follow the corporate hard line and eventually give up the job you came to do, be it analysis or software development or scientific research, in order to handle time sheets and mindless administrative tasks for a progressively larger group of people. The drive to bring in projects to make money also often leads to projects that are impossible to do well or with any kind of positive result - and these failures are passed down to the lowest levels - not left at the level where the decision was made to take on the project. These lead to low morale and negative feedback.