I have tried a few test campaigns with them and depending on your budget you can get a decent amount of impressions. You really have to get a premier location for your banner and find the right type of site/blog with buying traffic. I have broken even and made some money with my test campaigns.

You can test some smaller stuff for very little money so give it a try.

Do you mean as an advertiser or publisher?

yeah, if you dont have a lot of traffic you wont attract advertisers that are willing to pay that much.

I personally like PPC.

They are not good. Pay too low.