After playing the first four or so hours, the best way I can put this is if you enjoyed the old-school Assassin's Creed formula, you'll enjoy this.
Personally as someone who liked 2, Brotherhood, Revelations, Black Flag and Syndicate, this is right up my alley.
The biggest 'issue' probably is that the game hasn't really evolved since any of those, the AI is still dodgy, the voice acting isn't good and the story and combat are serviceable at best. It feels like a game that was and should have been released five years ago right after Syndicate.
But hey, I've missed these kind of games. I didn't mind Origins, Odyssey was somewhat good and I despised Valhalla but what I hated about all three was how dragged out they were with so much repetitive shit and a 10 hour story made several times longer due to the necessary grind. I'm not even joking here when I say in the first four hours here the story has progressed more than it did in my first 40 with Valhalla (and thank God I dropped it after that), this is exactly what Assassin's Creed should be.
But yeah, bottom line is if you're looking for an Assassin's Creed game like the older ones and can look through the flaws, you'll enjoy this like me and many others are.