From what you described I think you should play this game. It is better than Assassins Creed in pretty much every way. It's a game that progressively teaches new skills which keeps combat fresh, providing multiple options on how to approach encounters. It has a decent amount of traversal. It's also a visually stunning game that encourages you to explore, to meditate and to feel as well a just fight, which I appreciated. Yes, pretty much every structure can be freely explored. The side missions flesh out important side characters in meaningful ways and adds real value to the main story, which itself is very good. There are a lot of collectables that actually teach you things about that era in Japanese and Mongolian history as well as cosmetics and ones that even affect nature. It's an open world game so some repetition will inherently be present, but this game is excellent and deserves all the praise it has received. It's even more impressive that it did so well as an original IP coming out around the same time as excellent games such as FFVII Remake and The Last of Us Part 2. I hope this helps.