How is the game world in terms of beauty, atmosphere and detail, especially compared to game worlds like that of The Witcher 3, Horizon Zero Dawn or Red Dead Redemption 2. I'm a sucker for gorgeous game worlds. I can spend dozens of hours of playtime just exploring, marveling at scenery and architecture, taking hundreds of photos...if the art is great in a game.
I was just checking out Digital Foundry's video on the matter, but unfortunately for me the AC Odyssey videos were done by Thomas, who does of course great and informative work, but he tends to focus almost purely on tech and hardly on art and design, as John or Alex often do, which I always appreciate.
I tend to take lots of photos as well, and one of the less-mentioned features of Odyssey is that the in-game photo editor is very good, and also automatically saves pictures to Ubisoft's servers so it's easy for me to grab some examples.
Everything is from the base game on PS4 and taken just by moving around a bit in photo mode, to keep things sane I am dropping the image size substantially but hopefully they give some idea of how the game depicts its world.
You can swim anywhere, with lower depths having much less lighting and sea life, and surface areas having much more life and brighter waters. Whales will occasionally appear. They'll jump out of the sea when you're sailing. Underwater you can hear them sing.
Your ship is pretty well detailed and accurate to known Greek designs. Your on-board weaponry are arrows and javelins, which you can see the crew have safely and conveniently stored near the sides of the ship to make them easier to reach during combat. You can sail or row. Rowing means your lower deck crew drop these oars into the sea. Probably nobody in the world other than me checked to see whether those oars have different wear patterns on them, but
they do.
NPCs mostly walk around or don't do anything interesting, but you can come across people working, fighting, arguing, bathing, relaxing, etc. Environments aren't as well-detailed as Origins but there is still lots of stuff there. That altar in the background of that first image has votive offerings on it, and you can see different offerings on altars throughout Greece. Those guys in the second image are playing an early hockey-like game called keretizein. Those goats in the last picture aren't just randomly following that guy, he's a goat farmer and is leading them to the water nearby.
With some exceptions, things tend to look like they've been designed to work in real life. This torch, for example, is sitting in two metal hoops angled to keep the flame away from the wood. The hoops are held in place with a metal plate. The plate is screwed into the wooden beam. The torch itself has a handle, a guard, a wad of material to keep lit. Whatever is burning here is also giving off a blue-green flame, not just the standard flame effect. Torches and fire are one of the areas where Odyssey downgraded from Origins, but there's still occasional nice detail.
You can see this through the world - buildings mostly look like they'd work in real life, ropes that hold things together have knots on them, wooden beams are nailed or jointed together, and on and on and on.
Odyssey is capable of producing some pretty nice vistas. Background detail drops off substantially at long distance (base PS4).
Buildings and walls have decorations and carvings. If you catalogued them you'd probably find a lot of stuff repeating but in game this doesn't tend to be hugely noticeable (apart from statues which repeat very often).