Pros
Above average starting salary for my position, annual increases (even when Federal staff were not seeing them), very nice 401k match, lots of paid time off, flexibility with work schedule, responsive corporate support staff, great senior management team, and a particularly great customer environment. I was recruited fresh out of college by one of the owners, and was promoted 3 times in my first 4 years there. I would very likely still be working for them in support of the same customer if government funding for the program had continued.
Cons
Worked on a T&M contract type so government would not pay us for snow days or other closures. However, GAP Solutions management was great about letting me work longer hours during the work week to minimize impact from closures. This allowed me to keep some of my PTO for actual vacation days or to take paid time off following the birth of my children.