Vantaggi
NONE. They're thieves. You will get nothing out of working for them. Don't believe any hype. They're human traffickers targeting USNs.
Svantaggi
They will pimp you out to other companies. For example, Vectrus pays 3k monthly for a position, DAV FORCE will find a person for them and give that employee 1/2 the money. They keep the other 1/2. They'll then charge you for flights, medical (shots, physicals) and boarding. This is all supposed to be covered by the contractor. Former employees should SUE them together. They'll blackmail you too. IF you work in Kuwait, they'll block your visa from being released unless you sign a letter saying you'll pay them back. And they'll threaten to get you to lose your clearance. From the top to the bottom, this company is a P.O.S. There is a reason they're bottom feeders. They're parasites. Don't be led to the slaughterhouse. You will also have ZERO benefits. So- in review, they'll take 1/2 your salary and not give a dam* about you.