Why do people like Unity?

I just finished Unity after hearing from a friend that it's one of the better games in the series. I'm not any sort of Assassin's Creed fan, I've only ever played AC1 and 2 other than this. Anyways, after doing a few random side missions, but mostly the main story, I'm just wondering what has given this game the reputation it has as one of the stronger entries.

To me, the story felt very basic with a lot of characters that just pop up and become important/unimportant super quickly (Elise, Napoleon, a few others). I liked the ending but everything leading up to that was nothing inspired imo. The gameplay felt... floaty? If that makes sense? I often found my character would be moving and performing actions that I hadn't directly inputted, especially in parkour. On that note, there was really nothing super cool about it, I just held down RT+A and slightly moved the left stick. The side content was like, worthless, next to no side quests that contain cutscenes or interesting stories, and everything else is just "go to location, then open chest/kill 1 guy/walk over a cockade/etc. that would be finished in 2 minutes. Over half the map wasn't even touched in the main story which feels like a massive waste, why design a massive city if all you're gonnna fill it with is fetch quest side missions?

I didn't hate everything about it. It's absolutely beautiful, I love the design of Paris and honestly some of my favourite moments were the rift missions where you visit the city during the crusades, WWII, industrial revolution, etc. The setpieces, when they happen, were really cool and reminded me of Uncharted, especially the sword duel on top of the cathedral in a thunderstorm. The character customization was fun and I like making Arno some cool outfits, but I was a bit sad that it's next to impossible to make money in the main mission and you're forced to go out of your way to get rich enough to buy the really cool weapons/armour pieces.

Anyways, all this to say the game was just so... eh to me. Thankfully the main story only took me like 20 hours, so I didn't get overly tired of it at any point and was still able to enjoy the big moments in it. I don't mean to trash on Unity if it's anyone's favourite game, I just genuinely want to know what so many people find appealing about it. I haven't played many of the other AC games, so is it just that it's that much better than all the others? Or is there another reason?