Pros
Protiviti is a great place to start a career. For the college graduate, consulting / internal audit is great place to learn and experience multiple aspects of a business in a short period of time with little or no experience. Individuals who come out of consulting/professional services firms definitely have a leg up on individuals in industry as they have gained a set of skills in working between different groups and understanding how a business works.
Cons
The organization is still new although it aspires to be more established and well recognized. The Protiviti name is not exactly a "household" brand when it comes to internal audit and risk consulting - which may be a hard pill for the ex-Anderson types to swallow, but the company is pushing forward. Most consultants will spend a fair amount of time doing public compliance (SOX) work - which can get old pretty quickly if that is all you are staffed to.