Pros
I learned a lot about auditing, client companies' structure, and accounting during my first few years at the firm. I worked at a variety of clients, and working for different people helped me learn different management styles, which helped prepare me for the job I have now. As an auditor, you are exposed to so many different aspects of accounting that when you leave, you will get a job that is at a higher level than if you had gone into industry directly out of college.
Cons
I never received any praise or thanks for my work. The only reason I knew I was doing a good job was that I received positive performance reviews twice a year. E&Y's bonus program is a joke. They act like if you leave you will never get a raise or bonus, which is completely untrue. I left E&Y after 6 years and I'm making over 20% more than I did when I worked there. Also, the partners are completely inflexible, unless you are one of their "golden boys."