There was some hoopla a while back when they changed their process and everyone's numbers fell through the floor. Apparently marketing managers had been gauged on how successful they were at their jobs, with raises and bonuses tied to these Klout numbers. I stopped using it at that point.
They record how many people respond to your tweets/g+/facebook posts, how many followers you have and so on to give you a score, so you can do different things to improve. I think their income is based on outside advertising just like any other site.
Since you're a self-described social media lazy-person (and I don't mean that in a critical way), you probably shouldn't bother as you are already making sales from little marketing effort, but I think a fledgling interest in marketing will show that the more interest in You, the more in your product, and being able to measure that interest and guide it in a quantifiable way is important. As one becomes more influential, sales should follow.
I already know I would be a "0" on any barometer. I get no retweets and less than 10 views a day. Most views are robotic. No sense in wasting any more time in that area. If I get 6in 2013 or so sales a year, that's a miracle enough. That is more than I would get out of the stock market for $30.00. So I'm happy. In 2012 I got 4 sales with no tweeting, and I don't want any part of FB. I have enough work to do processing images.
I may try it out for fun! How is it really different than Google Analytic's? or any other site that measures traffic...Do they take the statistics and generate a report or statistic not measured by them?
google analytics shows you where people have been. this site just gives you a number based on whatever formula they use. it doesn't tell you much. other than i'm under rookie moms and obama. but i'm higher than billy.