Legion did not start out good, but it became good.
I think people forget how rough Legion’s start was. World quests were as bad then as they are now, but eventually we got both flying and the world quest group finder to make them more enjoyable. I mean, I remember tons of WQs I wouldn’t even touch before WQGF and Flying came around.
Ap built very slowly, but that was eventually fixed by a surplus of AK.
Legendaries were distributed unevenly and at too low a rate at first. I remember the day they fixed part of that because I saw one Tuesday on the forums a post “If you didn’t get a legendary before today, you’ll get one today from your emmisary” and lo and behold I logged in and got one.
Though not my own feelings, many people disliked Suramar’s design. Another issue fixed by the introduction of flight.
But there also was a lot of things to just really enjoy about Legion.
The class halls were great, and the class stories were so much fun. I actually leveled up nine alts mostly to see all the different stories and artifact weapons. I’ve never had more than three characters at cap before, but Legion made me want to do it.
Artifact weapons were great. They reminded me as to why I loved the original talent trees. I don’t care if a +1%dmg boost to a single skill is a meaningless advancement in the long run, it makes me FEEL stronger. and when it comes down to it, what I feel is all that really matters.
The combination of artifact skills and legendaries made me feel strong. It made me feel good. I enjoyed playing my cat druid, something I can very rarely say, because I finally felt like I had at my disposal the things I needed to make the class fun.
Leveling and gearing up alts was easy. The legion invasions and the gear vendors made raising up a new character a quick and enjoyable experience (again, nine alts leveled here). And, again, each unique class’s things prevented the experience from being monotonous.
There was a lot of flavor everywhere. I loved how NPCs would react to your weapons or your title. I loved the hidden skins and all the hidden secrets and interactions with your artifact. I never did find the ghosts of Arthas though…
Legion made me want to do things I hadn’t done in forever. I hadn’t raided since the beginning of MoP, Legion made me want to raid again. I’d never really PvPed, but I PvPed in Legion. When I first heard about the Mage Tower I was upset at the whole idea of it, thinking those skins would be forever denied to me, but I’ll have you know my main and all nine of those alts have every skin for their class (I never leveled a warrior and thus dont have those 3, the only I’m missing. I still don’t like the time-limited aspect of the tower and think people should still be able to earn them).
So, yeah, for my money Legion was a “good” expansion.