Pros
Good contacts and placements. I lucked out where I worked and made a lot of friends and had a good experience (with the full-time employees at that office, not the other contractors w/ADC. You don't really get much of that kind of contact with ADC.) The starting salary isn't bad compared to other agencies. It's a decent step for while you wait for your next career move basically.
Cons
NO UPWARD MOBILITY. I was shocked on my first day on the contract when the person training me (another ADC contractor) mentioned casually that she had worked for them for more than three years so far and had never had a pay raise. The health insurance options are insane. If I used their option (self + family), with the premiums, annual deductibles, and out of pocket maximums, it would've cost more than my entire annual salary! Just the premiums and deductible was over half my salary. Seriously. It's ridiculous that a company could dare offer a plan like that to employees. One year, our Christmas bonus was a $5 gift card to Starbucks. HR/Payroll are NOT helpful. They are unresponsive to questions, and they are very inefficient. One year I didn't receive a hard copy of my end of year tax forms until THE MIDDLE OF MAY. The online copy was available just in the nick of time before their legal deadline of the end of January.