nomis5 - 8:05 pm on Aug 11, 2011 (gmt 0)
I don't think success is limited to the US. I'm in the UK and last month Vibrant equalled my Adsense earnings. This month it is on target to beat Adsense.
I think my website subject is ideally suited to them and other subjects may not do as well but UK wise this is a real alternative that deserves a try by many websites.