almost 50% better frame rates, which made playing at 90 FPS throughout the game possible on low settings and playing at Ultra quality settings at 30 FPS a possibility as well.

The game also uses less power now while running at a higher frame rate.

Controller experience is also reportedly a lot better:

The gamepad [changes] are fantastic and allow you to use the inventory menu and others much more easily, making playing on the Steam Deck 10x better.