Pros
You mostly get to telecommute, especially if you're a PM or Engineer. Quarterly bonuses are good, but beware they are totally dependent on billable hours and "utilization", both of which are out of your control, despite what they tell you. The bonus and OT is great, IF you work 70+ hour weeks. Be sure to review the "compensation package" carefully!
Cons
Project Managers are not technically savvy and mostly mediocre. Engineering managers are always MIA and seldom reach out to their subordinates. There is a HUGE disconnect between pre-sales and delivery teams. Account managers and pre-sales engineers often over-sell solutions without understanding client requirements. Expect to be thrown into the wolves on short notice, being asked to jump into a project mid-stream with next to no information or requirements provided to you. Back end operations are sub-par, ranging from Benefits/HR/Help Desk to so called "service coordinators" who don't do much of anything. Expect to be double-booked and over utilized working on 6+ projects simultaneously. If you're a project manager, expect to manage two dozen projects simultaneously.