Deloitte's a good firm, but partnership structure creates a highly negative two-caste organization
Pros
Big, lots of different paths that can be taken within the organization. Firm has global reach, and lots of very bright and hard-working people. It will never hurt your resume to have a stint with Deloitte on it. The firm is by and large well intentioned, and generally comes out on the right ethical side of the issues. Senior management genuinely wants to make it a friendly place for people of all types and grades, but they don't always know how to bring this off successfully. Generally speaking, the firm attempts to do things in a first-class way, more or less.
Cons
The partnership structure creates an artificial and highly negative two-caste culture and mentality in the organization. The partners by and large make way too much money: in the private sector, most of them would have to take a 50% pay cut or more. Additionally, there is an excessive emphasis on billable hours, selling, bringing in revenues, which is at odds with the desire of the organization to continue being viewed as "different" from an ordinary "business" -- to be thought of as professionals acting in the public good. (That said, though, the organization mostly does make a positive contribution to, e.g., the transparent and fair functioning of the capital markets.)