Pros
At least they have temporary positions and handle that for employers. They are also located in many states and easy are easy to find. It can be used as an in-between measure for a job.
Kontras
Poor benefits, poor salary, no support from staff. No feedback. I have worked at the same company for six years and Manpower has not given me any raises, and look at me askew if I even approach the subject. It turns out that this company is closing and after two of us asking about future positions we have heard NOTHING in six weeks. Basically they hire you to work at one place and they stop. They'll collect their percentage and leave you there forever. I have resubmitted my resume numerous times, I have called about salary adjustments, and these requests are all ignored.