Far from the old multifaceted version, but providing some of the essential functionalities. I hope this is the beginning of the great come back of the refreshed Tab Mix Plus. Keep going, Dev(s?), please!

1. I can open links in a new tab just by clicking on them
2. I can have a list of tabs I have closed
3. It will remember what tabs were open when I last closed FF every time I close FF

I like some of the other things about it but those are the 3 most important.

There are so many different features in the versions before firefox quantum webextensions, which were nice to use, at some point important to have.
I love it and would like to have it back to the new firefox, therefore I also encourage a donation.
All the best for onemen!

Well, stares are actually for the purpose of this extension and to encouragement of the developer(s). Also for expressing the need of it. Anyway, after installing it, the middle click opening in a new tab of links did not work, so I had to disable it until further version. Thank you onemen!
BTW, I couldn't register on http://tabmixplus.org due to reCAPTCHA v1 being retired. Please fix it!

A good addition, but not all functions work.

I consider this to be an essential add-on. It greatly improves my Firefox experience.