Vantaggi
Some of them are meeting expectations but the assigned recruiters soliciting on behalf of their client's open positions are failing to meet those customer service expectations.
Svantaggi
These recruiters (1) don't follow up (2) but they continually blast emails at the walls "just to see what sticks" in order to meet their daily production (3) don't return phone calls to the very candidates they're sourcing (4) and seem to just be emailing bCC emails to networks when, in fact, the candidates don't meet the client's requirements but you won't know that until you actually (might) get one of the recruiters on the phone. Sloppy sales work; do your homework and get serious.