How does one measure success? By the number of Facebook fans you accumulate, of course! And Activision isn't at all ashamed of their following, now over a million strong.
Since the first Guitar Hero, more than 38 million GH games have been sold globablly, including 7 million in 2009 alone. Guitar Hero 5 has been doing rather well, of course, further padding the franchise's longevity and Bobby Kotick's pockets.
However, those figures can't compare to the series' popularity on social networking site Facebook, where it has attracted more than one million "fans." If you have an account, you can basically become a "fan" of certain groups focused around products, ideas or people. Guitar Hero has more of these virtual groupies now than any other video game featured on Facebook.
Hey, whatever makes Activision happy. If they're proud of their Facebook achievements then good on them! Yeah...