I upgraded the site to Drupal 6.3 today. I lagged a little behind but I was waiting for all my modules to be at least development releases and preferred that a majority be stable releases. So far the only one I've had trouble with is my Flickr module which was at alpha1 when I installed it. Hopefully I can get it back up and running soon. I rather enjoyed it.
One feature I know I will enjoy, hope works out and stops some comment spam I've had to administer, and I hope the occasional commenter I have will enjoy is the addition of a CAPTCHA module. Comments can now be posted without my administrative approval (the way I had set it up previously). So it should allow more direct feedback to those who post comments.
Cheers! I love Drupal, and the new release rocks my socks off even more. Keep on rockin' in the free/libre world :)