It's AC, so expect the world to be built as parkour ground for ancient would-be assassins, which delivers the usual hit to credibility. Despite that the environments look nice if you can get over the fact that, due to the large size of the world, everything is pretty much copypasted. I felt it was alright for smaller cities like Megara to be like that, but then I got to Athens and was hugely disappointment. Alexandria in AC Origins is far better, which actually should be expected considering that game only had three major cities (and Krokodilopolis), where as Odyssey caters to the entirety of ancient Greece, which was famous for its city states (meaning each needs some amount of respectful representation). Well, after lambasting Athens as copypaste shite I did warm up to it a little after questing there for a time. So I would say you can get over the sense everything in the game is generated from shared resources, as bummer as it is considering the franchise's history with city design. Such as it is I do find smaller settlements nicer, as they don't have to cover a lot of ground, therefore it's easier to design them with common structures.
Gameplay is similar to how it was in Origins, but combat doesn't feel as satisfying. I think it's tougher too, as I don't recall having this much trouble in the previous game. Died a lot in the early stages, though less now that I've unlocked Warrior skills and managed to get used to the gameplay. Even though the flow of combat in Origins felt better, the combat in Odyssey is weightier in a way that imo gives it more credibility. No matter your level you should have some trouble facing multiple foes at once. Warrior skills diminish this the more you unlock them, but if you keep a high-ish wanted level like I do there's often some tough opposition to make fights something you can't just phone in.
Speaking of the wanted level, one thing I really like is Odyssey's version of Shadow of Mordor's Nemesis-system, the Mercenary-system (wonder if Ubisoft got into legal trouble for that, since the system is under WB's copyright). Basically you do crimes like murder and thievery, you get a wanted level and mercenaries with some personality are sent after you, similar to Origin's phylakitai, just organic instead of a finite number of pre-designed foes. As you're a mercenary yourself there's a ranking ladder to climb, which nets you different benefits, and the further you get the harder your enemies become. Early on I relied on kicking everybody off a building, but at the level I'm currently on they all seem to be immune to it. You can pay a fine or kill a sponsor to get rid of your infamy, but I tend to keep it ongoing, as the wandering mercenaries actively hunting you makes the game more interesting (not to mention their loot is pretty good). This system leaks somewhat to regular enemies, as some enemy officers have shown to be almost as difficult as mercenaries below your rank. Most NPC's in the game, mercenary or otherwise, can be subdued and recruited to your crew as lieutenants, which nets your naval capability various perks and adds said recruit as a friendly combatant when boarding enemy ships.
That's right, seafaring is back! The core part of the best AC to date, Black Flag, I'm very happy to see it again. Initially I expected to find it cumbersome and kind of silly, as ancient Greece doesn't have the kind of ships 1700's Caribbean did (cannons, son!), but Ubisoft made it work splendidly; the Greek sea actually makes for a terrific setting for seafaring, and the trimeres of the era were very much used due to the land being coastal all around and islandy. Unlike in Black Flag you only use the sail at travel speed, otherwise it's all about people below deck using a whole bunch of oars, which (from my non-expert perspective) makes those tight turns more believable than they were in Black Flag. With the trimeres ramming feels like a core part of naval battle too, with arrows and spears (era substitutes for cannons) being in a more supportive role.
As much as I like the setting and the seafaring, the world does somehow feel less intriguing than Origins's Egypt. Ancient Egyptian religion and culture always felt more mysterious to me, what with all the pyramids and mummy curses, and I'm less familiar with them too than the done-to-death Greek stuff. Traveling around the Nile and the deserts and the old city of Memphis, there was a feeling of dread where ever I went. Odyssey has this to a degree with the antagonist faction, the Cult of Kosmos, but the land itself feels bright and chipper unlike Egypt. Without going too much into the plot (especially as I'm only, what, four chapters in?), it seems to be about the protagonist's bloodline, which makes the theme about family more than Assassin's Vs Templars, which Origins was largely about with Bayek's personal quest to destroy the proto-Templar faction, the Order of the Ancients.
I mean, sure, the Cult is still a Templar-esque antagonist faction, but they don't feel so mysterious nor the primary focus the way the Order did. Where Templar/Order targets were always plot-relevant big names, the Cult is a list of NPCs out in the world you discover by collecting clues about each one at your own pace. The Sages are the actual real deal (I assume, haven't unlocked any yet), otherwise you have a kill-list of people of little consequence or personality, kinda distancing the Cult from the main plot imo. Maybe it'll pick up later, but, conceptually, the cultist map turns what should be a core part of the plot into yet another Ubisoft bundle of chores. There's intrigue in hunting them down, but in a side-activity way. It doesn't help that the clue-gathering discovery tour is optional, you can stumble on cultists accidentally too, as I did in Attika, twice. In the first case I was puzzled why an officer among other guards was considerably tougher than the rest, then I got a slain cultist notice once I killed him. The other I accidentally killed as my mace swing unintentionally hit what appeared to be some random civilian as I was fending off guards.
I've otherwise enjoyed following the plot. Kassandra (of course I picked Kassandra) is a far better protagonist than Bayek, whose fundamentalist ways constantly irked me, and what we lost in the Cult's presentation we gained in personal impact. Kassandra travels the world pursuing personal goals and lives merrily as a misthios, mercenary. You get to make choices much like in Witcher 3, and while most don't have that much impact (if any) they do play their part in forming Kassandra's personality. There are also some choices that have actual impact on the world. Usually they're part of the main quest, but some side-quest choices have impact too. Here's an example: In Kephallonia a town was burned because it was plague-ridden. Only one family left and it's about to be killed by a priest. Prompting them you get to choose whether to protect the family from the priest or to let him kill them. Saving the family would be the "good" choice in a more generic setting, but in this case they are plague-carriers. If you save them you doom all of Kephallonia to become plague-ridden, while allowing the priest to kill them prevents this. I chose the latter so couldn't confirm the results of the former, but being a chicken I googled the consequences prior to making the choice and learned Kephallonia would go through visceral changes to the worse if you allow the plague to survive. Walking away after stating she wouldn't interfere, Kassandra was declared to have blood on her hands by the father of the family. This made me think of the trolley problem.
So for an AC the game does have a lot of personality and I really like the protagonist and her familial ties. And even though I'm not usually concerned by it, it's refreshing to see a good female protagonist in a video game (AC has already done well in that with Evie). I haven't tried Alexios, but playing as Kassandra the game very much feels like it was intended to be experienced as her.
I'm having such a good time with the game that even with all my criticism I'm giving it a 9/10. Subject to change if it takes a turn to the worse.