The new WordPress release is available since two days but it’s still too buggy to call it “final”.

Christa reports

…the dashboard is messed up, image uploader won’t work, the tags menu won’t work…or any of the other menus for that matter…

I checked this and this forums and they’re plenty of bug reports. It’s a good idea to not upgrade as long as most of these bugs aren’t fixed. If you already did here’s a description how to downgrade.

Update:
Code Styling wrote an article about known problems. He published some descriptions how to solve some of them.

If you are testing widgets on your WordPress powered blog it sometimes happens that the widget causes errors that make it impossible to remove the widget from the sidebar again. If these errors have bricked your system the only way to get it working again is to deactivate the whole plugin. But if you would like to use some parts of the plugin that are independent of the widget you can’t just reactivate the plugin because the widget will be present in the sidebar again. For this reason I wrote a plugin that removes all widgets of deactivated plugins from the sidebars.

Downlaod