Most companies hate using them, and in my current job search I have opted to not use them this time.
Depending on what industry you are in, they will charge a huge fee to any company that employs you, they may even charge for putting you forward for interview.
You are much better researching the companies you are interested working for yourself and sending them applications.
Recruitment consultants IMO are a waste of time, and are just pushy salesmen who never stop calling you even when you are in a job that they put you in, they still keep calling to see if you are interested in moving so they can make some more commission.
Grrr and indeed Grrr