Drupal 6

With the recent launch of Drupal 6, I wanted to start some dialog about transitioning to the new core. Has anyone moved their sites, or created any new sites in Drupal 6? If so, what were the snags (if any) for upgrading? I have most of my Drupal installs at 5.5+, so just curious to see if there are any early adopters out there.

James