In a word, I am hugely impressed! I loathed WordPress 2.6.x and all it’s incarnations. It was a pain to navigate, clunky and just felt so delicate that I was afraid to even tweak my heavily modded K2 theme. Normally every WordPress upgrade ends up breaking my theme and I spend weeks re-writing sections of it. After the RC1 installation, much to my surprise everything was perfect and I cannot see anything out of place anywhere.
The new Administration panels are a joy to use and uncluttered, yet compact. Discussions are much easier to see at a glance on the dashboard thanks to the new comment features – you can now directly reply to a users comments and your comment will be updated in realtime beneath it. The whole overhaul is a breath of fresh air compared to version 2.6, which I regard as the poorest release of WordPress I have seen. I now await the full release on December 10th. Have that date on your calendar folks!