Great to see Mozilla consistently improving devtools in Firefox. I have been using them over Chrome for a while now, hope it gets to a place where most devs start using FF again for debugging web apps.
The CSS Changes page is a godsend. When editing CSS live it collects all the changes you've made so you can then go back and apply them in your codebase without having to hunt for them in the page elements.
They have some experimental features enabled there which they don't in other channels.
For example, I'm running Nightly, and the Dev Tools>What's New tab says the "Debug Variables with Watchpoints" (break when a property is read/written) feature is in Developer Edition (and presumably not in Nightly or the Release channel).
It is somewhat newer than mainstream, does not require to enter "yes I'm sure" when opening the dev console and has actually a beta qualifier as version number. I haven't run into any stability issues though.
> DevTools’ Network panel can now inspect WebSocket messages and automatically formats a variety of framework formats
Finally! This was the main reason to develop on Chrome instead of FF for me. The rest is almost comparable with Chrome DevTools for everyday web development.