Pros
After having worked at Booz Allen for five years, I can say that there are a lot of awesome things about the firm. It's a good place to work, with pragmatic management that make generally intelligent business decisions. The ECAP contribution is outstanding, and I had consistently fantastic administrative management. Salaries are generally consistent with market competitors (e.g., Deloitte, PwC, CEB) but I've heard of the occasional massive bump, though its not typical.
Cons
With that said, its easy for an ambitious young person to "hit the deep end of the pool" in terms of what the firm can offer. The business model is designed for "command-and-control"-style business development and responses to client RFPs, which is stable (to the extent that the government pipeline is consistent) but doesn't engender a ton of entrepreneurial spirit. The firm isn't positioned to do work on small strategy teams, preferring to launch massive, expensive engagements (which is very pragmatic and stable, but boring). Finally, its becoming a bit hard to determine what the firm's strategy is in terms of the commercial / international market. Even though it claims to be interested in the space, I haven't seen much progress.