Pros: they can get you jobs that you aren't qualified for
Cons: horrible benefits, get one week vacation per year only if you reach 2000 hours of work in that period
Probably one of the lowest paying staffing agencies. All places I've worked at had other agencies bring in people at at least $1 more per hour. Company pays the same for contractors, ProStaff just takes more. Their payroll department also has a constant habit of "losing" timecards.
Work for them as a contractor ONLY if you have no other options. I'd recommend Aerotek, Addecco, or Express over these guys any day. You'll get paid more and receive thank you gifts more often ( bringing in pizza and stuff )