I did an upgrade of my site to Drupal 6 this evening and so far everything looks fine. If you encounter problems, let me know! Not depending on cck & views is a major advantage even after D6 is out for almost two months now. In fact, I only have the spam module to replace - or find another solution - because there is no 6 version out yet for it. For now you always must preview your comment, I wonder (probably naively) if spambots can circumvent this ;-)
I've tested D6 a few times allready at work, but not on a production site yet. The drag & drop features and the actions/triggers module are really wonderfull and I'm sure I'll discover some more cool features in the days to come.
update 2/4 : I just installed mollom on my site, so you can now submit comments directly!