Vantaggi
Worked as a "Student Services Contractor" for the EPA's Office of Research and Development; very intelligent and driven coworkers made it easy to get engaged in the work. My supervisor (mentor) was thoughtful and made an effort to connect me to projects that I was personally and professionally interested in.
Svantaggi
No PTO, benefits are quite terrible, and your Federal employee colleagues, while well-meaning, will treat you like a second-class citizen because they know you're a short timer. There's no real pathway to convert from an SSC position to a Federal position, and it doesn't even give you a leg up in applying for a Federal job. Many SSCs have graduate degrees (including doctorates) and are established working professionals in their late 20s and 30s, yet are treated like college students.