Pros
If you work hard and demostrate competence at your job you will be promoted to at least senior associate, things get a little more politcal at the manager level. You will have an opportunity to work on multiple engagments (depending on the office) and with many different people. The job will challange you and you develop accounting/auditing skills very quickly. Partners and senior management have been around along time and are usually well connected in the community and they are good people to know and leverage from. The benefits are good, some of the best in the Big 4. You get 25 days of vacation and I have never had any trouble getting time off.
Cons
The hours during busy season are brutal but probably not any different than the other firms. KPMG technology seems to lag behind the other firms and our methodology can be redundant at times. Employee ratings can be political and are often not based on performance (i.e. hours worked, deadlines met, professional credentials earned). There is little chance of being promoted outside of the normal process (2 years Senior Associate, 5 years Manager, 7 year Senior Manager, 10+ Partner)