[CedarDave]

Here is an older thread that details the damage the new version will do. The main problem is that the new version automatically will make just about ALL extensions obsolete. Only a small number have been rewritten and available for use with this new browser configuration.

Mozilla Will Kill Legacy Firefox Add-Ons in Exactly Three Months (Now November 14, 2017)

[oh8eleven]

the new version automatically will make just about ALL extensions obsolete.
Yep. Just installed it and it sucks. How is grossly changing the GUI, and killing all my add-ons an improvement? Morons.
Was able to find a Mozilla website that has legacy versions and re-installed v56.

[yefragetuwrabrumuy]

That did kind of annoy me, about losing some useful extensions, in the the replacements offered for the most popular of them aren’t as good.

You would think they could at least put out a request to extension developers to prepare new compatible extensions ahead of time.

Three I lost included Bookmark Favicon Changer, Flash Controls and NoScript. NoScript Suite Lite is far less flexible. And now I have to pause stupid autoplay videos on every dang news site.

Oh, yes, it also bollixed up my font sizes, ignoring old HTML font sizes. Oh, you wanted the picture 200% size, so obviously you want your fonts 200% larger as well.