Pros
Lots of brilliant and clever longstanding employees, but loyalty is usually rewarded with distrust and criticism. Work is challenging and repetitive but you can learn a lot and get good exposure to big name clients.
Cons
Every change made by the current management seems to be to negatively impact employees and claw back benefits. Compensation for mid-level and below gets worse every year in real terms. It is well known that HR will rarely reply to anyone, even once failing to respond to a colleague trying to hand in their notice. Seems to be an inner circle who will endlessly be rewarded while others are punished and blamed for any problems. Terrible and laborious review processes. It was never perfect but better before the private equity takeover.