Pros
Your experience at Booz Allen will be largely dependent upon your manager (FLL) and project. I've been fortunate enough to stay billable during my time here (approx. 8 years) and projects have been challenging and engaging. Work / life balance and flex-schedules are a big selling point. Yes, there are surge periods of proposal work, marketing, white paper, etc but to be objective, most of our work schedule is M-F, 9~5. For a 'consulting' gig, this is more than reasonable. If you're just starting your career or an experienced hire looking for work / life balance, Booz Allen is the place.
Cons
As I stated earlier, your experience at Booz Allen will be largely dependent upon your manager (FLL) and project. I've had some TERRIBLE managers and Senior Associates that showed little to no empathy towards their people or their development. And there does not appear to be any incentive for them to change, e.g. as long as they bring in the contracts. If you're looking to advance beyond Associate, you'd better network, network, network, build your business case, and win those contracts. Otherwise, realize you'll be an Associate for the rest of your time at Booz. As others have stated, Booz Allen's compensation is below the mean.