I unsubbed around two months ago, turns out you don't need an active sub to play on PTR so I've been playing the 9.1 content for a couple weeks. I haven't seen anything yet that makes me want to renew my sub.
The world content isn't bad, lots of new cinematics and story. Being able to mount in the Maw and fly in the SL zones is a nice (intentionally withheld) QOL improvement. Casuals can grind the new zone to eventually get roughly heroic raid level gear (237 and heroic is 239) but it's not clear yet how long it will take (it will take a long time, likely months).
Torghast changes kinda suck so far as it makes you want to rush, even if you don't want to. I completely ignored the timer/empowered bar and full cleared everything at my own pace on layers 8-10 (202 aff lock), even went AFK for 5-10 minutes sometimes, and got 4 stars consistently. Still some of the torments/blessings really make you want to rush, like I got this lightning orb one that charges up while you are moving so you end up running around in circles around the mobs every pull like a spaz. It's looking like it's going to take 9-10 hours of runs to max out the new talent tree if you're efficient.
I don't raid so I can't comment on the new raid, but I will say making the new dungeon Mythic only is clownshoes and tone-deaf if they're trying to retain players.
I don't want to play FF14 as it's not my style, but damn, their devs actually care and communicate with their players. They are not too stubborn to admit when they are wrong and constantly make changes to fix things that suck with the game. Their subs are booming as most games are, where as WoW is the only major game to actually lose subs during the pandemic. I can't even imagine how dismal their metrics would look if they weren't propped up by Classic and TBC.
TL;DR: Check out 9.1 for a month if you want, unsub until 9.2