Pros
Great learning curve for technical aspects of your service line (Audit, Tax, Advisory) and there is absolutely a benefit to learning how to work hard. A large part of the market value of a KPMG alumnus is the ability to work hard without expecting very much. Lots of Vacation time right off the bat.
Cons
There is a heavy focus on keeping associates, seniors, and to an extent managers, away from real quality discussions with clients. I personally felt like my public speaking, interviewing, and general discussion skills suffered after 2-3 years being told to stay back and work, as opposed to creating relationships. There is a big focus on "chargeability". While this is beneficial for the company, it almost expects employees to forget that every hour of overtime they work reduces their own hourly value. Work/Life Balance is only an initiative because otherwise it would be SO BAD. Vacation is plentiful, but is often needed just to de-stress from the work. On that note, see discussion with management on vacation