Just gonna try and give a quick overview of my thoughts about 15 hours in without spoilers, bear in mind that this is from the perspective of someone who generally really enjoys AC games and open world games in general.
Combat - Pretty good imo. There's more emphasis on parrying and dodging than usual in an AC game, particularly when playing as Naoe. Timing counters etc is pretty fun and there's undodgeable attacks you have to evade, certain classes you have to break stance or parry or dodge to attack head on, so it's less just walk into an area and swing like a maniac and smash everything than usual.
I wouldn't say the swordplay is as advanced as GOT as I haven't found it's got the stance changes mid fight etc and building skills out of different stances at least yet (it'd be late to introduce it at this point) but it's fun. So better than average AC but not as good as GOT in that regard for me.
Parkour is okay, kind of what you expect from the newer games. You've got a grappling hook which gives you some options, but none of the newer games are as smooth as something like Unity when it comes to traversing rooftops so it's not a return to that level but if you enjoyed the way it worked in origins or odyssey it's fine here, probably a little better in the sense that you can't just climb up anything by pressing up and do have to think about your route sometimes.
Stealth is good imo, plenty of options for ways to sneak into places. Usual issues with enemy AI where once you're prone on a rooftop for a minute they forget you just murdered half their mates but that's Assassin's Creed.
Game world I think is incredible from what I've seen so far. Areas are distinct from each other and I haven't really come across any big expanses of nothing yet. Lots of settlements, temples and castles dotted throughout the landscape.
Story wise it's fine so far. Both characters make sense and their backstories check out so far. Nothing I would call woke at all. I don't think any AC game is going to wow anyone with the storyline and writing but while it's hardly the Witcher 3 it's fine as an entry into the AC series.
Graphics are beautiful, but you can probably see that from any promotional material.
Scaling is good, lots of different options for upgrades and skills to unlock.
Base building is very good if you're into that, lots of different things in the game world you can collect for your base and lots of buildings you can throw up which gives you more scouts and helps your allies giving you motivation to collect resources in the game world.
Weather effects are some of the best I've seen.
Getting about is fine, usual markers, pathfinding and fast travel options. A lot of the viewpoints are in castles which I found a bit of a pain really as I don't really want to have the option to fast travel to the centre of a castle to attack it in a mission but it is what it is.
You don't have any bird this time but tbh I think that's better and you don't have the temptation to just send the bird to ruin the game world for you before you get there.
Mission wise it's the usual AC stuff. Meet someone, go to this area to look for them, track them down, kill them, maybe do a few other things before you're able to. Rinse and repeat. Same as any AC game.
A bit jumbled but those are my initial impressions without spoiling anything, but if you like AC games in general there's no reason you wouldn't like this one.