Anybody Using The Latest/Newest Version Of Firefox?

I use it on one system... and yes it is faster.
Downside is.... if you use a lot of addons, they may not all work.
Out of 6 addons I use, only 2 work on the new Firefox.
Have purposely kept Firefox from updating on a couple of systems because I have addons that I need.

 

I use it on my Linux system and have had no issues with it as of yet.

 

I run FF ESR as a backup browser. I won't have to deal with the legacy addon mess until the end of June 2018. By that time, perhaps the addons I currently use will be available for the new extension system. I might dump FF. I've been trying out Vivaldi on my 32 bit system and WaterFox on my 64 bit system as possible replacements.

I swapped FF as my main browser for Palemoon quite a few years ago. It is faster than FF and the few addons I use worked. The theme I always use, Walnut, didn't work but someone wrote a theme that did called Walnutty and that works perfectly. So I've been pleased with Palemoon. Since then it has forked away from the dependence on Mozilla. It has its own addon system.

 

Yes, that's the reason.
One of them.. 'Malware Search' hasn't been updated for a couple of years ( it doesn't need to as it's just a link to many malware removal databases) and isn't likely to be updated in the near future.
But another 'helper' has written a similar version that is compatible with FF57.