An interesting "feature" of sorts in the new Web Inspector is that if you right click in the inspector pane itself and choose Inspect Element you get a second pane displaying information about the inspector itself (see linked screenshot). You can in fact keep doing this recursively on the inspectors, though it quickly triggers some bugs where the layout breaks and you can no longer resize the inspectors. These layout bugs can persist even after closing the inspector and require restarting WebKit. So, despite the cool "meta" factor of this it'd probably be best to disable the behavior.
Otherwise first impressions of the new Web Inspector are great and I hope it will replace most of my need for Firebug.
I think this is a good thing. Especially for developers who want to write their own extensions to the Web Inspector:
Maybe have this ability be a toggle-able setting or a defaults key/value?
"These layout bugs can persist even after closing the inspector and require restarting WebKit."
I agree that this is a real issue that I've run into.
This is meant for debugging, but it should be a hidden option. We should also never dock an Inspector in the Inspector, also use windowed mode.
This is no longer relevant since "Inspect Element" is hidden by default. Although, it is possible to turn it on https://bugs.webkit.org/show_bug.cgi?id=80585#c4