Pros
You gain exposure to a number of industries. Also, you have a slight degree of flexibility in your ability to transfer between offices (although area management will resist). E&Y is a good place to begin a career, or work towards partner if you have no life and enjoy monotonous, boring work.
Cons
Offices tend to be very cliquish. As much as management likes to promote a "work/life balance", there is absolutely none. Even if you have no work to do, you are expected to meet your minimum number of hours. The work is extremely tedious and boring. The client doesn't respect you or go out of their way to help you. You represent nothing more to them than additional work that they must do. As you advance through the firm, the normal people will drop out and the only people left will be the tools who are bent on becoming partner.