Pros
Quality of clients and good access to the consultant base, the large engagements in Detroit are isolated from the rest of the firm but if you work you can get access to the knowlege sharing databases etc. When working for Accenture I had far better access to talented people. In general the consulting staff was far more competent than the local yokals hired to staff at the client. Most were people from non consulting backgrounds or from industry. Their thought leadership was limited. However the consulting resources from the true consulting organization were highly skilled.
Cons
The downsides are if you are staffed long term with one of their large business process outsourcing groups you may not get senior leadership with the wide levels of experience and client backgrounds that you get in a true consulting org. If you are with consulting services the standard for an employee is higher and the quality of leadership is higher.