Pros
I worked for Marcus & Associates for just under 3 years. John and Ellen have great relationships with amazing companies. I joined M&A in 2009 when the job market was horrendous but M&A had plenty of jobs with top companies because of their long standing relationships with them. John and Ellen truly cared about me and we still keep in touch. I learned many important recruitment lessons from them, things I still use every day.
Cons
If there is a con, I would say that at least when I was there, the business operated as a generalist firm in Accounting & Finance. They worked with top companies across many different industries and while there were benefits to it, at times I felt spread too thin, not having much of an area of specialization.