If I had to rate this on a scale of 1-10, I would've given it a 7 out of 10. However, on a 5-star scale, I leaned 4 because overall I enjoyed the game.
At first, the game felt like a knock-off of God of War with some similar features/gameplay, but once I got into the main story it felt more like the typical assassin's creed games. I just finished the game, and after completing the main story, the Asgard story, the Order of the Ancients tree, and gathering all wealth, I put over 100 hours into the game - very very solid.
Overall, I really enjoyed the game, but there were a couple of things that I didn't like. First, I've played every AC game since AC2, and I recognize that as the games go on we get further away from the originals. However, Valhalla specifically puts absolutely NO emphasis on being stealthy/sneaking around. If you like a lot of fights out in the open, you will probably enjoy this game more than I did in that aspect. The stealth part of "assassin's creed" doesn't exist in this game.
Second, some of the staple AC mechanics in this game are horrible. Climbing up structures and through windows can be VERY frustrating and there have been times where I have restarted the game because I couldn't climb through. My BIGGEST complaint, however, is with the Leap of Faith jumping. In a lot of the synchronization points, it is unclear where exactly the hay pile is, and you end up missing and jumping to your death. I'm not exaggerating when I say that I jumped to my death at least 10 times, even when I was aiming for the hay pile.
Overall, solid game, a lot of content but won't wow you. If you want an enjoyable, time-eating game it's a good pick.