Pros
Overall the company is stable - economic lulls aren't met with widespread layoffs. You have a level of autonomy as far as what time you start your day and how you organize your deliveries and customer interaction. With the right manager you are encouraged to make front line decisions on a lot of things. There is no "I have to take this to my manager for approval" - you handle customer issues on the spot, and the better you are at selling yourself and your company, the more successful you will be. You can go days, even weeks sometimes, without having to answer to a manager at all. There is a concerted effort to make the company fun and playful in nature - by and large the people that work for the company are amazing. I met a lot of good friends at the company over the years, people that I have continued to keep touch with, who still work there, and who have moved on.
Cons
There is no union. Your salary and commission structure may be changed at a whim, and your options are basically to either threaten to quit or just take the pay cut. The program that the sales reps sell is not the same as what you are asked to do by management in the service department. Example: Sales reps key on excessive replacement charges from competitors, and state that Cintas doesn't do such a thing. As a SSR, you are asked to charge the customer 20% of their revenue for replacement on every invoice to meet your job performance. The downside of all the autonomy you get is the level of responsibility you have - sometimes the hours are very long when your goal is to have every customer very satisfied. If you are unhappy, things will quickly grow very uncomfortable for you there - people are expected to always maintain a positive outlook regardless of what your situation is.