Pros
Everybody has heard of the company, you don't need to explain what your employer does. And for newbies to the industry, MCW does a great job of orientation and training new employees. The company offers good benefits and pay, though they have been pared significantly for new hires since 2007. The Purchase HQ and grounds are a beautiful place to work, but isolated if you're used to the bustle of Manhattan.
Cons
MCW is a remarkably bureaucratic environment and often hard to get things done in timely, efficient manner. For all the talk about acting with a sense of urgency, even a simple project can drag on for months--thanks to the "matrixed" environment, buy-in and consensus is required for just about everything, and is often an excuse for manager and lawyers who don't know anything to stick their fingers into your project. (In fairness, I've been told this is beginning to change under the new CEO who just came in.) But an awful lot of what I did was "meta"-work -- work we had to do to prove to somebody else in the organization why we should be allowed to do our real work our way.