Pros
The product they have created is probably one of the best analysis tools on the market. It is remarkably easy to use, learn from, and totally worth a trial, just to see how it works. Personnel wise, their hiring process is rather strict, but fair. They have a heavy engineering culture, and encourage personal projects to be done to forward the company. The office I was employed in (Mclean, VA) has an interesting set up, and it is growing quickly. Little scooters are given to move from office to office, and you can get nearly anything to make your office your own sort of work space. Food wise, they have a caterer or cook set up, and there are free beverages, all of it available at all hours (Keep this in mind). The pay is above average, with a cool way of setting your own payscale. When an offer is made, they give three different offers, with three different stock options (5 year vesting schedule). I would guess they pay above about 25-50% of the average amount.
Cons
With all these benefits come a drawback. I estimated a average work day of around 10 hours. I would start at 8 AM, and leave at around 7 PM or so, an only in the first week. I expected these hours to go up as time went on. The food and pay are high to encourage you to remain in the office, and the standard work week is discouraged. Although they like to say they observe a Work Life balance, I generally could not see it happening, especially with such hours. Travel, you can expect to fly out to another location fairly regularly on short notice. Don't expect to make any real long term plans, and prepare to live out of a suitcase for more than a few weeks out of the year. Finally, the management wants you to "Drink the Kool Aid" rather deep. They try to indoctrinate you into their methods of thinking and working before you even start working there. It seems to be based on T-shirts and clothing, more than anything else. If you are not a estimated "fit" within their box of thinking, expect to not get an offer, or even be let go. I would be extremely wary of any "Openings" found within the Department of Defense section of this company. It is large and growing, but the leader of this section has been described over and over as "Intense". Be very careful of what you say and who you speak to in this company, or you may find yourself without a job with no real warning.