Ventajas
(For the contracts I've been involved with) Good place to get your feet wet in IT desktop support roles if you have little to no experience. Management is usually not very technically inclined, so it's fairly easy to get your foot in the door with little to no experience or schooling. That being said, it's advisable to have a general interest, basic knowledge, and the ability to learn quickly for whatever roll you're applying. CompuCom will pay for certs. My advice is to use employment with CompuCom to obtain that 1 to 3 year standard experience requirement (and maybe some certs) then move on as soon as you find a better option, or are ready.
Desventajas
If you are in a 'High cost of living/pay' city or region, plan on pay that is well below industry standard. Do not expect raises or meaningful recognition. Obtaining either of these is like binding your feet and hands, then going for a swim. Available Medical insurance for regular non management employees is horrible, but available.