Pros
ADP is a large, financially stable company which offers a breadth of opportunities. They have a decent benefit package when it comes to time off as a pension.
Cons
The compensation policy seems to be pay the minimum possible and only adjust when an employee makes an issue of it. At that time they either perform and adjustment or let the employee walk. This is exacerbated by the small pool of money allocated for merit increases on an annual basis and the small promotional raises (4% for 1 level, 3% each level after that). Recent reorganizations have eliminated most of the middle management roles so advancement is extremely difficult. Senior management espouses horizontal experience as a replacement for progressive experience but internal hiring managers do not.