Like Origins, this game was a let down. It's beautiful and the art department did an incredible job. The story is interesting but the good stops there. This game is so painfully slow that I gave up playing 3/4 of the way through.
Every mission requires you to be a certain level, and the missions don't level you up enough to play through the game uninterupted (unless you pay for microtransactions). This means you have to crawl through dozens of side quests and grind constantly just to continue the story. This is really slimey design on Ubisofts behalf and totally unlike the games before origin.
The problem is that once you've played the game for a few hours, the mechanics get boring, the combat stale and the side missions repetitive. The map is an absolute pain to get around, being a similar size to black flag but the constant back and forth between locations makes it feel like you're really walking across greece. Fast travel requires you to jump to the top of a monument which gets old after the first 10.
The most annoying thing is that they seem to have given up giving the world outside the animus any real narrative like the first four games. I haven't played valhalla but i've heard they're using a similar formula.
Personally i would like to see a game less focused on repetitive open world elements, which was never Assassins creed's strong point, but more focused on combat mechanics, story, characters and interesting missions.