Gnome 3.6 beta has been out for a while, but not available for testing without compiling the software, so I was pleased to see that a live image is available- basically running on an alpha release of Fedora 18.
I was familiar with what was coming from a post at As far as I know. There are descriptions of changes with screenshots there, so I'll just add a few personal comments.
The new message tray is a big improvement. The jiggling small icons which are so hard to click on have become fixed, large icons. The new triggering mechanism seems a bit coarse, but an improvement is planned.
The centralised search bar in Activities Overview, now minus application icons, really emphasises the way to use Gnome 3: not by searching through a screen of icons (which, after all is really a Windows 3 paradigm), but by entering the first letter or letters of the application you want to launch. I'm finding this a much easier way to launch applications than by searching though menu items.
The new Nautilus looks very good. Gnome is about minimalism and I like minimalism. There's been a lot of negative comment on the new file manager because of lost features. When I first heard about the dual pane feature of Nautilus being dropped, I was at first concerned, because I use it a lot. However, I listened to the justification given and it seemed reasonable: a new "move to" feature largely removes the necessity for a dual pane, and if you do want to compare files in two locations, side by side view is easy in Gnome 3.
Gnome 3.6 really looks like being something approaching what Gnome 3 should be. As a Debian user, I'm sad that it's Gnome 3.4 that's going into the next stable release. Debian Stable Gnome users will be missing improvements in Gnome 3.6 that see the desktop get into its stride after some initial stumbling steps.