It's definitely worth a look I think. Just make sure you fully understand their fee structure before signing anything - they have the potential to be very expensive if you're not careful.

A lot of the really good ones can add value in other ways as well; in the past I've had recruiters get us presenting at events without having to pay sponsor fees, free conference tickets and training vouchers for successful candidates, pre-baked employment contracts and other HR-ey documents you can use etc etc.