Graphics wise the main improvement is the lighting; in 2020 it looks so flat and uniform and bland, now it's much more dynamic and nuanced. The main villain also looks literally a generation ahead of how he looked last year.
In terms of gameplay I'm getting a bit of a Doom Eternal vibe from the physicality and pacier flow of combat, which is a great thing in my book as I loved Doom Eternal, and it doesn't seem to override the classic Halo feel. It looks really satisfyingly crunchy in terms of feedback and movement, which is awesome.
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023. (And over 130 million lifetime)