Pros
Paychex is family oriented and has a very flexible work schedule. They also have a very good benefits package, but they revoked the 401k match in 2010.
Cons
The client support at Paychex leaves a lot to be desired. As a sales rep I got to the point where I couldn't in good conscience sell certain systems or services because I knew they wouldn't work and the client would call me to complain. I was tired of fielding customer complaints. I felt bad for them and it was really hard to get back end support to resolve issues. The other major problem I has was the paperwork. It was not only hours of work for the rep once a deal was signed, but they make it very hard for the customer to get through the set-up process and go live. I had a number of new clients sign the contract but never go live on the service because the process was too laborious.