They have definitely made huge improvements since the April-May 2020 build they showed at the July 2020 show, textures for armor, vehicles, weapons, and the ground massively improved, lighting improvements, reflection improvements, no more glaring pop-in issues, etc. All were very much needed changes, and the game looks good enough now imo.
That being said, it still doesn't look as good as I would have imagined it would look after watching the initial Slipspace Engine teaser they released in 2018, that 2018 tech demo had amazing, next-gen graphics at the time, whereas Halo Infinite very much so still looks cross-gen unfortunately. It's a real shame that they didn't aim for more on the technical/graphical level, especially since they've basically said this will be the only mainline Halo game this whole generation, with new singleplayer and multiplayer content being added as DLC for Infinite instead of new Halo games releasing. Maybe they will improve the graphics for future singleplayer campaign expansions and make them PC/Xbox Series only, but the multiplayer will be looking the same the whole generation most likely since they won't be willing to cancel support for the XB1 version and go PC/Xbox Series only, which is to say it will look pretty dated within a couple of years as Xbox Series/PS5/PC only multiplayer games start to release, and even more dated in the 2nd half of this generation, until around 2027-2028 when the next-gen consoles release, and we presumably see the next mainline Halo release.