My husband tried it for awhile - it does work, but you need to get enough people on your blog to actually click on the links - and you're not allowed to ask them to do so.
His blog wasn't too popular - so he only made a couple dollars - and I think you can't get a check until you reach $100.
If you have a lot of friends that would participate - you could certainly make some money. It was pretty easy to set-up.