Pros
This is one of the largest architecture firms based in New York, and there is job security: the company is seemingly a place where one could work for the remainder of a career. I believe most employees stay for this reason in addition to inertia. There are also many studios at Perkins Eastman and transition from one to another may help your experience. The hours can be very reasonable.
Cons
Low budgets are the driving force of projects as well the driving force for an employee's experience of the office. Employees are not rewarded on merit. Very small bonuses, no in-house printshop (therefore cannot be used unless specifically commissioned), sad, banal office culture and parties/events... There is a general lack of design intent on projects. Managers control projects (under the tight scrutiny of the senior managers who have to enforce strict hours due to low billing, which results in usually less-than-mediocre work); designers are Photoshop-ers. There is a very high turnover rate at S9.