Staffing Agency? I need advice

hello everyone! finally, i got my working permit and ready to work in a dialysis facility. i have 1.5 years of experience in this area when i was in the philippines. i found few jobs online, like in fresenius and davita websites but the facilities are in the bad area. it's my 4th month here in dc and i really want to work in a safe area. now, i found jobs from the staffing agencies online and they are in a much safer place and close to where i live. my question now is what are the disadvantages of applying through an agency? may i know as well what are the advantages? your insights are highly appreciated. thanks!