I've just done a test upgrade from 1.5 to 2.0RC3, which was pretty smooth (I did get a database error, but ignoring it seemed to work :)
The obvious first difference is the editor, which is now WYSIWYG by default - great. However, I only get two buttons in Firefox (1.5 on windows), 'split post' and 'help'.
Is this a known issue or is there something strange about my installation? I've disabled all plugins remotely to do with editing, and although I have a lot of extensions in Firefox, I can use TinyMCE elsewhere (e.g. on their site). Internet Explorer gets all the buttons, but is not my prefered browser.
Is there any documentation on the WordPress version of TinyMCE? I'd quite like to investigate. I also noticed that it doesn't deal with nested lists properly, but that's another kettle of fish...
Thanks for any tips... :-)
(FYI: The database error was "Table 'wordpress.wp_usermeta' doesn't exist".)