I've now created three different Drupal 7 sites, and I can heartily state that I'm pleased with where the community has come in the past couple of years—especially from a UX perspective (the admin overlay has actually turned out to work VERY well across all the browsers I use). I will be posting more impressions of Drupal 7 from a themer's perspective in the coming weeks (check out an older post on D7 theming here).
I'm going to attempt an upgrade of this website to Drupal 7, then walk through creating a new D7 theme (hopefully to be contributed back) for this site.
Now that D7 has hit release candidate, a full release (1.0) can't be too far off, and nothing helps improve Drupal more than to start moving smaller production websites on shared hosting servers from 6.x to 7.x! The more people that do this, the more people can help fix the lingering bugs that are keeping Drupal 7 from more widespread adoption by those already using Drupal 6. You see... everyone benefits!
Sadly, there are two or three sites that I won't be able to upgrade to D7 for a little while, since they have a boatload of custom code (although the Coder Upgrade module/site is extremely helpful for upgrading this kind of code!), and a few crucial D6-only modules.