Pros
You work alongside some very intelligent and talented individuals. There is much expected of you here and you will be groomed for future success at future companies. Needless to say, the name in itself will open doors for you as well.
Cons
It is so large that the culture resembles a big bank and less a small hedge fund. The politics are severe and despite your loyalty to the company, there is no loyalty to you. Make a big enough mistake (and it need not be large) and you are gone. Just had a kid? Bought a new house? Fallen on hard times? They don't care. Cross them, and gone. Just like that. Also, there is no support or guidance. People are quick to fault find and finger point so don't dare ask a question or you will become the butt of gossip as an incompetent who should not be working at mlp. They are also a bit on the cheap side for compensation and benefits.