I don't mean to be that guy like I was with Black Flag, but Assassin's Creed Odyssey was not made for the AC series. It's a great game on its own, but I think the only way it actually ties into Assassin's Creed is through the Isu blood/goddess blood shit that HARDLY makes any sense to begin with, as well as basically being the start for the Order of the Ancients which eventually become Templars which eventually become Abstergo. In this game they're cultists who worship a tiny pyramid that gives them glimpses of the future that they think comes from some kind of god. But besides that, most of the actual main story is basically reuniting your family, and it's quite frankly kind of boring up until you finally meet the main character's Mom. That's besides the point, though. I really don't understand why they tried to pass this as an AC game when it could've just been its own IP. It doesn't really explain much for the actual story besides something that they might try to tie in with Valhalla, but it's honestly just a low point for the series in terms of story. However, combat, exploration, side content, and world building are handled greatly. I kinda don't like how they treat some of the historical figures of this game. I don't think anybody historically has really gotten much respect out of these games since AC4 with Black Beard and Mary Read. They all get treated like comedic relief in a way and it's just kinda weird to see. Let me talk about combat real quick, though, because despite me saying it's great, it's also kinda just gross how many hits an enemy will take before dying. It's better if you spec into a bow build like I did where you can just headshot most enemies from a bush most of the time. That, to me, is fun. I love doing that. Especially since these games were originally made with stealth in mind, it's nice to have that back. It's just done in such a forceful way. The exploration is also great just for the fact that there's a lot to explore, and it's all detailed very beautifully. My only complaint there is that there are too many army camps and not other unique locations, so you basically still get the same issue I had with Origins where there's just too little stuff in between all the big stuff. Side content and world building kinda go hand in hand because so many things can be different based on your approach to something. Often times I'd be stuck between 2 people who each want me to do a different thing with the target I'm going after, and I just fucking love ignoring them both and killing the target right away, then coming back to find they're both pissed at me, but also happy the target is gone. There's also so many other super major events that really make the world feel huge and mystical like how we all think of ancient Greece, but it's all the Isu's doing because they gotta tie it back somehow. There were so many things I loved, a few things I hated, things that genuinely shocked me, and overall I feel like this game is judged too harshly for making the same point that I made: That it's not Assassin's Creed. Put that aside and it's still an amazing game overall.
Edit: I'm putting this in way later because I forgot about the modern storyline. A-whoopsies. Yea, nah, I hope that really highlights how forgettable it is because the few time you're outside the Animus there is nothing of substance to do, see, or discover. The only thing I can say, is that Layla isn't as insufferable as she was in Origins.