While I can't wait to use the new trigger/action features in Drupal 6, I have a feeling it will be a few months before I attempt to upgrade. Apart from Views and CCK not available, the number of issues fixed between RC4 and RC3 looks awfully long to me. This include 17 critical issues, 26 normal issue, and 4 minor issues. Some of the critical ones, like #218471 and #214209 can be nasty if not cought. From RC2->RC3, there were 107 issues fixed, so the number has gone down more than half, but there seems like some way to go.
The release candidate says
Drupal 6.0 final will be released after (a) there are no more critical bugs and (b) we've had at least one release candidate without adding any more to the list.
Since there are already 2 new critical bugs reported since RC4, there will at least be RC5 and RC6 before Drupal 6.0 is finally released. And I might wait until 6.2 before upgrading the production site. (Since 4 sites run off the same code base, ichris.ws will have to wait as well)
Now, I do have one running D6 installation at GARP Thailand, since that site doesn't use many contrib modules (my other site uses 61 on last count). I should stop complaining and go test it some more.