It's actually interesting what is going on with user interfaces... Basically little by little, everything migrates to WYSIWYG-style. Squarespace 6 was a step in that direction but created a very strange environment in which you could edit the site "inline" or on a different UI. And some things would be editable in one place, others in another (e.g. sidebars would be configured in one place (show/hide/left-right), and populated in another). It was very strange, but, at the same time, it would make it cleaner to see the preview without a lot of menus appearing when you mouse over things, etc.
Now Squarespace moved to their version 7 and pretty much got rid of the non-inline editing mode. Now all my edits happen directly on the preview. It's pretty cool as a technology, but it does bring an interesting set of challenges. For example, on the SJC website if I hover on the menu on top in edit mode, there is an overlay of "Navigation | Edit" that actually covers part of my menu! Also sometimes my mouse is hovering on something and I don't notice and suddenly there is "extra content" on my page that I didn't expect.
But it does streamline editing. I haven't played with it that much, but I think it's a step on the right direction. The most important thing that they did right this time, that they couldn't do with the Squarepace 5 to 6 transition is that it's a feature that I can turn on for my website and not a matter of redoing the whole website as they required for the previous transition. Great job, Squarespace!