Pros
Training is top notch. Very educated and technical peers also abound when you need references. Updates are quickly disseminated when a new law gets passed that may impact your work. It's great experience before leaving to join industry or other places. Many skills are transferrable.
Cons
Hours are the worst for those in tax department. Had some work weeks as low as 55 hours and then other weeks close to 90 hours. Staffing and turnover seems to be a problem. That can be frustrating when having to retrain new employees. Also PwC is not up to modern standards when it comes to telecommuting. Instead it is allowed only for managers. Makes sense to offer some days each week for those who opt to telecommute. Another downside is politics but you can't escape that anywhere.