Hello quit,
I don't know in which city you are living, so I can't tell you whether or not agency is useless. But agencies don't give me any help except giving me experience how to deal with HR guy.
I have ever met more than 3 agencies, none gave me a interview opportunity. They just asked me some questions, let me describe my projects, which technology I know, etc. Then, they told me they will arrange soem interviews for me. But I never received a call from them. I refused to meet the fifth agency.
I got many interview opportunities by myself and got a offer several days ago.