Pros
I worked as a permanent placement recruiter doing Accounting & Finance in Chicago. I was hired into SNI from another staffing firm where I had been for two years so I was experienced & successful. SNI promised cutting edge technology, high commission percentages, and relationships with companies that are impossible for most recruiters to break into. Everything they promised to entice me to jump was a lie. This was the worst run place I've ever worked. Extremely high turnover on the permanent team, even in an industry known for high turnover. The sales tactics are abhorrent. Only place I've worked that actively pursued references simply to prospect those people. My manager constantly ran fake job ads to collect resumes. We hired tons of people straight out of school, promised them a three month 'runway,' but fired everyone after two months, even those that had success. In fact successful people were the best to fire because management would take over their relationships with good candidates. Run away.
Cons
See above for further detail