Early feedback indicates that June 8th was a successful World IPv6 Day...or should I say lack of feedback. But in this case no news is good news. Despite an occasional IPv6 reachability issue perhaps due to IPv6 inexperience, no widespread or even moderate connectivity issues were reported for IPv6 or IPv4 connections.
As reported by the Internet Society, sponsors of World IPv6 Day, nearly all registered participating organizations truly participated and measured IPv6 traffic was up sharply compared to nominal IPv6 traffic, though still miniscule with respect to overall IP traffic.
So while scalability testing was not in the cards, hopefully participating organizations have garnered "lessons learned" about implementing IPv6. Scalability testing will inevitably come with time with an increasing IPv6 end user population. So now's not a bad time to get comfortable with IPv6 when demand is low...for now!