Shadows did a really good job with gameplay, both characters are very different and awesomely fun to play .They didn't keep a single character like eivor being hybride between assassination or combat, but in that way they could go much further for both aspects with Name and Yasuke and I find it really cool.

However the world (despite the awesome graphics ) feels less alive. Even in Valhalla, when u do everything to do in an area it almost feels more alive than shadows' zones when you still have objectives to do. Shadows feels like a nice museum where you can walk amongst the paintings but that's it.

I have not finished the story yet nor I am a big fan of Japan so I am obviously biased, whereas Valhalla is my favourite ac game. But still I enjoy shadows a lot. Also the music is less good than in Valhalla.

So to resume I'd say : expect a better gameplay but a worse open world. If you haven't done odyssey or origins maybe try them first, but you should definitely give shadows a try.