Commission Junction's advantages over AdSense?

Google gets the best position always and is about 80-85% of earnings through the year. But in Novemeber December and January that seems to flip to where google is is only 45-50% (at least in Dec), even when it has the better spots.
However i do use the CJ datafeeds and target the products. The one thing I would suggest is staying away from the CJ banners they dont even come close to returning the amount you can get from individual products. Also the items are condusive to Christmas shopping.
My Google income acually drops during this period but not much, its more that the CJ stuff goes crazy. Its the end of October so I'm already starting to see the effect.
In my opinion CJ is pretty comparable - but you need to do quite a bit of work to get it going. Google does all the targeting for you.