Pros
Booz Allen has done a smart job of documenting and structuring the firm. The way the business side is run can be very personality driven as each partner controls their own business. But the people side is pretty good (though personalities obviously vary by team). HR is responsive, collaboration is understood as a key to good business, management is generally willing to be transparent and communicative. Professional advancement is encouraged and cultivated.
Kontras
Professional advancement is not always encouraged and cultivated with the employees broader goals in mind. You have to be very pro-active in knowing what you want and vocalizing that. Otherwise they are going to look at the experience you have and put you where it works for the business, not for you. The culture is on the conservative side, most people still wear at least a tie, many a suit. That shouldn't be a surprise, it's a client facing business that deals with the government and the military so they are inclined to present a particular image.