I think iAd works best when it's possible to create a fresh immersive experience. If you're only using the platform to repurpose content a user could easily find elsewhere, it may not be worth their time or yours. If the product or message supports development of content that provides value, entertainment or otherwise, for a user, the platform offers ample opportunity
Tapjoy is awesome when you wish to advertise your app. User traffic can be achieved through campaigns. The engagement rate can be increased, which in turn increases business sales. The smart search option is very accurate and time-saving; I was able to search the term like ticket id. High revenue can be achieved.
In some instances, we developed an experience for AdMob simultaneously with our iAd experience, working with both teams on a daily basis. While the Google team was skilled, receptive and helpful, Apple device functionality was broader and thus allowed for a little more imagination in bringing intuitive relevance to the creative content we developed
They have very different model of business, but I would use TapJoy as a complement of this other products. So you can expand the inventory where you buy ads and be able to scale more rapidly the growth of your mobile app.