Pros
Industry specific knowledge from some of the best professionals in the field. If you work hard and give good impressions, partners and managers will trip over themselves to coach and guide you. There are ample opportunities to learn other skills such as technology applications. KPMG will not do the work for you - you will need to be proactive to get the most of the company. I have also grown personally - going from an extremely shy and nervous person to leading client meetings with no stress.
Cons
During busy season, expect 70-90 hour work weeks (not including crunch times near issuance). But you also can't report your real hours as that messes with the budget so everyone lies about how much they are actually working. I myself have witnessed coworkers experience bullying, isolation, mental breakdowns, and mental health issues such as depression and anxiety stemming from this job. this is entirely team, location, and industry dependent, so one person at KPMG can have an amazing experience while another person can have a horrid experience. WORD OF ADVICE: DO NOT JOIN IF YOUR MENTAL HEALTH CANNOT HANDLE IT. You will not be able to keep hobbies or spend a lot of time with loved ones (including pets) during busy season, so it will be extremely tough mentally.