The HTML editor that is enabled for Plus users is now a configurable option.
If you know that you don’t want to use the HTML Editor, for whatever reason, just go to Customize, General Diary Options, Basic Settings and take the tick out of the HTML editor box. You’ll then be reverted to using the normal editing box.
Hope that helps those who don’t like the new editor!
Please remember, the HTML editor is for Plus account holders only, so you can’t make it work unless you’re a Plus!