Pros
Paychex is a very stable company. As long as you are productive you do not have to worry about losing your job due to outside variables. The benefit package is a plus. Medical, vision, dental, 401k, FSA and a slew of other employee friendly benefits are available. Corporate leadership and values.
Cons
True job promotion is limited. SLOW steady progression is the path. Many lower-level positions are created to encourage "job promotion", but it is basically a false promotion that is used to keep the masses chasing the carrot. The wages are low. Your performance is definitely not tied to your annual review or raise percentage. You can provide 110% while someone else provides 60% and your raise will be with .25 cents of each other. This is an area that definitely requires improvement. Local leadership/values are not consistent with National/Corporate leadership.