Pros
My experience with Adecco was good overall. It was my first and only time working as a contractor so I have no other jobs to compare it to. I was fortunate to have a great project in an incredible working environment. I found Adecco's reps to be very responsive to my questions and needs; the hourly wage was at the high end of the pay scale amongst other contractors for the same position; and the company appeared to have a solid working relationship with the project company.
Cons
These are probably standard for contractors but the biggest cons included: no benefits, no employer matching for the 401k, contract-based work (not Adecco's fault), and no career development. And I didn't feel like Adecco would find me work elsewhere had my contract not been renewed consistently.