Personally I hate them...here is my experience with Robert half in Grand Rapids Michigan
I get a call from a Robert Half head hunter wanting me to drive to his office (2 hours away) for an interview.
So I get in the car and drive out there...once there they inform me I have to fill out all the tax forms w2, a non-compete and a non-discloser agreement - before I could even see the Head Hunter for the interview...or there would be no interview at all.
After signing my life away I got an interview with the guy who kept getting calls on his cell phone...after the 8th call he finally looked at my resume....then said "great lets get you tested". He then sent me on a 3 hours drive in the opposite direction to get tested because he did not have time to test me there.
After spending 5+ hours on the road with 10 minutes of interview time I made it to the test center and was tested on:
Windows Server 2000
Windows Server 2003
Microsoft C# Programming
Microsoft VB.Net Programming
SQL Server 2005
I aced all the tests (still have the print outs to prove it).
He called me a month later and told me that he never submitted my resume as he felt I did not have the skills or personality that would mesh well with the job...and then hung up on me.
I then go out and find my dream job by myself without the help of any head hunters.
About six months after that he calls me and litterally BEGS me to drop everything and take a job that is a 5 hours drive away for 1/2 of what I am making. I told told him no and asked him to not call my house again. Then I hung up the phone.
He called back instantly and threatened to sue me for not taking the job, stating that I signed an agreement (none of the agreements said I was obligated to do anything other then not compete against them for the same job).
So I forwarded the paperwork and agreements to my lawyer and had Mr. Legal tell Mr. Half to shove off or I would sue them for harrasment and unfair business practices.
I am sure not all Robert Half head hunters are like that - but that entire thing really made me not like them
Just my two cents worth... head hunters are evil and I avoid them at all costs after that incident.
For the record, I have 12 years experience as a professional programmer and 6 years experience as a network admin...this was definatly not my first time dealing with a head hunter but it will probably be my last.