Not sure how you prefer bug reports, but here it is:
When I have the WordPress admin bar enabled, it throws off the placement of the editing button and left-hand border. (It moves down the same height as the admin bar and this makes it hard to use.)
That said, the new style of editing is one of those knock-your-socks-off experiences. In the future I suppose this direction will be obvious: "Of course we should be able to edit web pages directly! Of course, of course..." But for now, it is cutting edge.