[mattgratt]

Allegedly they don't take information from analytics. (Most of the important metrics they could probably get from something like G-bounces (when you press the back button and go back to the results page) or other sources like data from Chrome or social data.)

It's free b/c it helps marketers measure and optimize their Adwords spend, and justify it to their managers. (Most search advertising requires cumbersome custom tagging - in Google Analytics, Adwords is basically integrated automatically or with one click.)