I've been using D7 to get familiar with it, testing / writing patches,
and to begin porting my contrib module. It is awesome, but the one thing
that sticks out to me is the inclusion of Overlay in core.
Why are we including Overlay enabled by default in core? What functional
purpose does it serve beyond eye-candy? I realize that it potentially
allows you to remain on your current front-end page while doing some
admin tasks, but isn't that why tabbed browsing was invented? This
breaks anyways when you get redirected with a drupal_goto() somewhere.
My biggest complaint is that It slows down the admin work of the site
considerably, at least in my workflow.
I don't mean to take away from the work that was put into overlay - some
very talented people have put a lot of time and effort into building it,
polishing it, and fixing some oddball performance issues. But it just
doesn't seem to stick with the core philosophy.
At least this module should be disabled by default in core.