> Since some Web pages may appear broken when elements that track behavior are blocked, we’ve made it easy to turn off Tracking Protection in Private Browsing for a particular site using the Control Center.
Whitelisting a whole site because it "appears broken" is a pretty weak approach, and clearly incentivizes "brokenness". I notice the spies (google etc.) are more intelligent and creative than the defenders of privacy.
We need a browser that can make such sites work - for the user. Without leaking any cross-site information. This involves rewriting URLs and cookies, or "mixmastering" identifiers across a cloud of users.
>Today we’re also releasing new visual editing tools in Firefox Developer Edition including Animation Tools that work the same way animators think.
To me this sounds like fiddling while Rome burns.
Typical of their track record of wasting energy on irrelevant projects instead of making a great browser.
I don't think you're being fair. I'm seeing a lot of improvements from Firefox, outside of their vastly improved developer tools and tracking prevention.
* They've been working on multi-process Firefox,
enabled in developer edition 
* They've been beating Chrome's JS Engine in the
benchmarks (not to mention IE) 
* They've been implementing more and more of HTML5, about
81% of the way there according to 
* Firefox supports more ES6 features than Chrome 
 - https://developer.mozilla.org/en-US/Firefox/Multiprocess_Fir...
 - http://arewefastyet.com/
 - https://html5test.com/results/desktop.html
 - https://kangax.github.io/compat-table/es6/