It is and it is not. Have to be very careful when selecting the web site where to place your ad. Some web sites convert very well but some not. Also It depend very much on the ad position. On one and the same web site I had one ad , let say ad_1. It was running for one month and because I was happy with the performance, I added a second ad_2 there that links to different web site. Meanwhile, the order (the sequence 1-st, 2-nd, 3-rd etc. ) of the ads located in that column changed and my ad_2 become on top of the column, while ad_2 was shifted to the mid of the column. The performance of the ads changed immediately. AD_2 now gets 6-7 times more clicks than ad_1. So, it is a bit of luck too.
I hate adsense theere check out system is really annoying when i was ordering a ad place it auto adds Qty.2 when i delete it it comes back after 4 times of trying i get it working then when i ordered it they took 2 payment on the same day then kept taking money from my bank every few days my bank cancelled my cc and counted it as fruad when i logged into my adbrite it said reacerrance which means it will keep buying i didnt even want that and i didnt even choose that on the checkout it dose not even ask you anything about it. I would say stay away from it. The pusblisher account is ok tho.