There’s a whole list of websites that are trying to compile the working addons for the WoW Classic beta. The easiest one to parse through is Will It Classic. The site has a list of addons — including a search function — and has color-coded each one to signify whether or not it’s working on the beta client. Keep in mind that the client runs on the Legion API, so there are a few semi-current addons that work without any tweaking by their creators.

Brewmaster: Hot Trub - Purifying Brew deals 30% of your purified staggered damage to all enemies within 10 yards. Mistweaver: Way of the Crane - Increases your Physical damage by 25%, you remove and become immune to all snare and root effects and you heal up to 3 nearest allies for 150% of all damage done. Lasts 15 sec. Windwalker: Reverse Harm - Heals a friendly target for 8% of their maximum health, and causes 100% of the amount healed to instantly be dealt to the nearest enemy as Nature damage within 5 yards. Paladin
Recently the new essence received from PvP which gives you access to an extra PvP talent, that also works in PvE situations, has made waves and there are plenty of threads about it on the forums. One in particular got a blue response which clarified just how powerful and how relevant the essence is supposed to be for PvE-focused players. Each spec gets a specific PvP talent added and some of them currently selected on the PTR are a little too powerful and feel mandatory for PvE, such as Moonkin Aura for Boomkins and Leader of the Pack for Feral Druids, but Blizzard clarified it is not their intention to have must-have talents for PvE available through the essence, as its primary goal is to add additional choice for PvP players.
I think this may have been a case of that specific sword simply having wildly inflated secondaries. If I recall correctly, when I played during Wrath, +STR and +Hit were the stat kings for plate DPS classes (I remember all the guides recommending +STR gems in every slot and +STR enchants on everything) and secondary stats were, well, secondary, and inflated secondaries on a weapon weren't that big a deal. But now that secondary stats have so much more importance, I suspect that an "outlier" weapon like that just wreaks havoc with modern calculations, so that all the addon sees is that this particular sword offers +15 more Haste and Crit than everything else that drops.
Azeroth Auto Pilot est un addon qui a servi à Method à décrocher le world first niveau 120 en moins de 5 heures de jeu. Programmé pour vous faire suivre le chemin optimal pour monter de niveau, il s'agit non pas d'une aide, mais d'un véritable GPS qui vous indique quelles quêtes prendre, où aller et dans quel ordre faire les quêtes. Cet addon est recommandé pour les joueurs qui n'aiment pas prendre le temps de monter en niveau.
We have no idea what implications this might have and whether or not it even indicates anything, since Patch 8.2 is still in testing and a Tuesday launch is more than unlikely due to Essence tuning and Azshara's Eternal Palace, which is supposedly coming shortly after launch. Blizzard said they wouldn't be delaying the new raid like they did with Battle of Dazar'alor.