I switched to YPN late last month from Adsense. I was making $N/day with Google, I'm making $N*4/day currently with YPN. I've already made more since I've switched than I've made in the last two months with Adsense. I guess it depends on the site and the kind of traffic it gets.
Most of the ads I have from YPN are well targeted; better targeted than Adsense's ads. Plus the CPM seems to be much better. I'm actually averaging less traffic and making more money, go figure.