https://www.pcgamer.com/assassins-creed-odyssey-will-be-much-longer-than-origins-but-should-it-be/

Assassin's Creed Odyssey will require more of a time investment than Origins, according to game director Scott Phillips. Speaking in the video above to Game Informer, Phillips is asked if the game is about the same length as Origins, and answers "No, much longer." 

You can find this at 3:06. Phillips doesn't elaborate on that, but he does explain that the map is bigger and more packed with things to do. "There's a ton of stuff to explore and find and discover." We pretty much knew this bit already. Odyssey's map of Greece will of course feature numerous islands, and the return of naval combat. Check out the full map in the video below from my hands-on earlier this year: