I've used recruiters in the past and have had mixed experiences. Overall I do not like them for one specific reason: They are not working in your interest and apply pressure similar to what you would expect from a used car salesman. The thing is though, you are not a used car and choosing to accept a position is about your life.
Smart Money has nice list of 10 things about recruiters that you should know:
1. “There are better ways to find a job.”
2. “We don’t work for you.”
3. “Until a year ago, I was a car salesman.”
4. “The job we advertised may not exist.”
5. “We already know quite a bit about you.”
6. “Our jobs aren’t so hot either.”
7. “You’re at the mercy of a computer, just like online job board users.”
8. “The ‘temp-to-perm’ carrot is rotten.”
9. “If you have a job, I could get you fired.”
10. “If I’m in Virginia, I probably won’t help you find a job in Nebraska.”
You can read the whole article here.