I think I'm in the minority but I've never really seen the appeal. I've always much preferred chromes developer tools. Right click on anything and choose 'inspect element' to see what I mean.
And on my Chrome, there is a regular inconsistent bug that when I want to inspect an element, the new tool UI is displayed but the element is not selected.
I've never used Chrome so I don't know if it's better or worse.
My point though is that it's first in recent years that we've had tools like these, and they made a huge difference for me helping me undesrtand what the hell goes on with the styles. It's a much nicer workflow than the old edit-reload-check-edit-reload-check model, where you inserted coloured borders to see exactly how large your divs were, and moved things a few pixels at a time until it looked right.
And on my Chrome, there is a regular inconsistent bug that when I want to inspect an element, the new tool UI is displayed but the element is not selected.