While I do understand that core team is working on 5.7.0.1 release with marketplace integration and all kinds of fixes, I think we should be already discussing about the next steps of the in-context editing UI. Many aspects of the new UI works just great, but there are some irritating features (or "featurelessness") that take a big step backward usability-wise. At the moment there are some threads here and there (even in bug tracker) talking about how to improve the editing experience, but I think we should try to keep the discussion somewhat centralized...or has it already moved to GitHub..?

Anyway, here's my concerns/comments:
1. When adding or moving (dragging) a new block, you can't distinguish normal Areas from Global Areas. This may lead to some page-spesific content being unintentionally all over the site. The user has to memorize areas by hovering over them in edit mode.

2. This is probably the most discussed one: Areas not visible in edit mode. Bad for theme development, unintuitive for user. My suggestions: Make the areas visible right at the moment user starts to drag new or and existing block. This would still be a clean and 5.7-ish solution, even though I personally still prefer seeing all the areas in edit mode all the time so I can actually just take a quick glance and know where I'm able to add content, without hovering all over the screen.

3. When adding a page, the mixed use of composer and edit mode feels kind of uncanny. No improvement suggestions there though...I have to use it more and see if I get used to it :)