I've used them before for advertising. Their bidding system sucks and you need to watch your traffic. Other advertisers have figured out how to bid on the same domains and will end up redirecting your traffic after you've paid for it..
For example i bid on domains for registry repair applications. I would get a hit and send them to my site, not but 2 seconds later the same IP would hit the site again but this time from a different affiliate id... sneaky little fuckers.
you also have to baby sit the bidding system. if you auto-set to bid the highest, when the price drops you will still be paying the highest.. sometimes it can mean a difference of 10 cents a hit..