Pros
In terms of places to come out of school and learn a lot about the way that the federal government and business work together, I don't think you're going to find a better place. We really do work hand-in-hand with our clients unlike almost any other firm. Plus, as you do well accomplishing your difficult assignments, you will find that there are always opportunities available for you to do more and more challenging assignments. Those challenges might not always be ones that you would personally choose, but you'll usually be challenged.
Cons
Getting stuck on a client site engagement can be an absolute killer to your professional development. Despite the firm's move towards a more decentralized intellectual capital community, you are still extremely hampered if you're not in a Booz Allen office. Once you get placed on site, start working on an exit strategy.