I signed up as a publisher there but never got to do real tests.
My initial experience as a publisher wasn't all that smooth tho. Let's put it that way. Their CPM was really low. donno if bc I was just testing them out with small sites or if that's what they actually pay. I do know each campaign is dealt with your manager, they negotiate rates for each campaign IIRC (haven't used them in years), so maybe if I'd shown them more traffic, they'd given me a better deal.
After a few emails back and forth, they stopped replying and I couldn't get more sites approved, so I just stopped publishing their ads and moved on.
This was a couple years ago admittedly, donno if things have changed since. Curious to see how it works now.