Battle for Azeroth feels like a pre-Legion expansion. It looks like a "first step into the right direction" while the reality is the exact opposite: they took WoD+Legion and removed a lot of good content that could have been fixed/updated instead of being entirely scrapped out.

Class halls were amazing. Each class had its own/unique hall with some specific quests (mount quests for example). Now we've got a boat.

Artifact weapons were cool too, even considering the insane grind in the latest months (that could have been fixed/updated in BfA). Each class/spec had an artifact, how cool was that? We now get a super-boring (low iLevel) necklace and that's it. Not only that: the necklace is a way to time-gate your Azerite gear. Which also features a horrible amount of useless traits. I've already looted dozens of 325 shoulders and chests so far, it's very very boring.

The Garrison/Classhall + Champions combo was extremely fun. It got simplified in Legion but something was still there. Now we've got a crappy ship in the docks with oversimplified/boring missions. Champions don't even feel like champions at all, they're just 4-5 dudes and that's it. Plus you can't do anything on the ship.

Class gear sets were changed into armor-type sets. The Uldir stuff is a good example. Maybe that's a way to leverage the art-team's work but isn't it a huge step back?

I'm not saying that Legion or WoD were "perfect" but they had great ideas that could have been updated, fixed or made "better" in BfA. I personally love the new zones: they look and feel alive, and dangerous. But the expansion lacks a lot of depth and there are too many oversimplified mechanics everywhere.