Verdict - It's like flavored, cheap gum: It tastes nice at first, but you regret chewing it after a while.
This game made me never want to play another action adventure game again. The premise of it was great: you play a viking clan leader, trying to find a permanent home in Brittania. You have a settlement, you can upgrade it, go on raids and make alliances with different regions. Battles looked fierce, it had a large map and lots of different quests to pursuit.
I stopped playing Assassin's Creed games after Ezio's story ended. I also didn't play any of the games after the gameplay style "reboot" that started with Origins. Valhalla was a fresh experience.
First 15-20 hours were great. I didn't mind going with NPC's to the quest areas, were eager to do more raids and keep the story going. But after the 20-30 hour mark, the game became so repetitive and dull, I started to distance myself from the game. I played it a few hours each week. It took me a year to complete the game, hence the date of this review. You feel like you've seen everything after 30th hour, and the game keeps giving you the same type of quests, similar dialogs and side quests that you regret after completing them. I managed to finish the game in 90 hours. Assassination skills and stealth are meaningless and doesn't reward the player in any way. I tried to clear every region I went to fully, and I leveled up so much that I managed to kill the final boss in 2 hits. World map is very large, and there are large empty spaces that made exploring a chore. Going from one place to another takes very long, and even main quests make you listen to an NPC that talks to you while you go to his hunting lodge at the very end of the map.
If the game had cut its map size to a one third, and made the game shorter like 20-25 hours, this would have been a great game. But here we are, playing a copy and paste, bloated Ubisoft game again.