I want to start with the fact that Assassin's Creed series is my favorite. I played all games (twice), completed everything 100%.
I was excited about Valhalla, but for me it was a huge disappointment. Reasons are many, but just to say a few of them... story doesn't have a good narrative, the lack of a main villain is felt, game is way to repetitive, there is nothing new after the first two regions. They fact Ubisoft said the enemies will be smart and adapt was a huge lie. The game is pretty easy even on hardest difficulty. You just have to learn how the enemy reacts. I can continue with the fact that Ubisoft does not relate anymore to the assassin vs templar war - I am sorry but the assassin's are kind of side story here - or at least it doesn't feel you have something in common with them. You don't even become an assassin. And if they did not finish the story and they will finish it in the DLCs... that is just taking their community as stupid folks. Anyway...
... the biggest disappointment was the fact the Ubisoft does not fix the game. The main focus for them is to add new SF sets with lightning and fire and stuff, to sell for 20$ (when the base game is 60$). And I would not have a problem with it if the game was flawless. For instance today I entered again the river raid - because they said they added a new set. By the way... river raid is the most boring, repetitive, without content stuff that was ever added in an Assassin's Creed game. So I entered again, got 350/400 supplies, I am near the final chest, I fall through the ground, I die and I lose everything. Because Ubisoft is not fixing the game. I swear, I do not know why I should enter this game again to do this. It is so boooooring and you die because Ubisoft does not fix the game.
It feels so bad to see Ubisoft not care about this instead focusing only on new gamers who do not know the lore of this saga and care only about hack'n'slash. It feels so bad to see this happening to your favorite game.
~an OG Assassin's Creed fan