Fair chunk of the way into Odyssey since starting around Christmas. It's huge, and I'm level 51 but I've only just reconnected with my father in that weird island location so feel like I'm still a way off the end of the main story. Over half of the cult are dead, I hunted all the open world ones down when I was able but they seem to be attached to questlines now so progress is slower. I am one of those people that will just hit a new island and go to every camp, fort, cave etc so I reckon the story will take me back to some locations I've already 'cleared', but that's okay.
I'd say to anyone starting it now to completely ignore all the 'hourglass' icon quests you run into. I didn't realise they were generically generated things and was picking them all up and running all over the place to deliver a letter, or kill 4 bandits, and as a result I got 'overlevel' for most of the starting zones very quickly and it never really normalised. By the time I got to the arena the first guy was easy pickings (most things level up with, but slightly behind you but the Arena challenges are set level that never changes).
I've only played Black Flag before so can't really compare to most AC games but I do like this one, somehow they seem to have crammed just about everything in from Greek history and mythology without it becoming too nonsensical.