I just discovered it last night when I went to write a new blog post. I simply cannot praise it highly enough. I love the new "Quick Press" box, and the fact that when I save it as a draft, I don't have to leave that screen to edit it; the link to it is right there. It's so much more streamlined and efficient than the old interface. It looks better, too.
Awesome job, all you WordPress geniuses. :-)
Keep up the good work!