While Hades II feels in many ways like a complete game, as Supergiant's roguelike is still in Early Access, there are plenty of things that will be changed. The biggest changes will come in the game's first major content update, slated for later this year, but in between now and then we have a new patch to pour over.
This patch does add some new gameplay elements. Namely, you'll get new incantations at the Crossroads Cauldron, all of which will give you small but meaningful buffs, like gaining extra life or magick when picking up resources, or being able to slow down time during the Chronos fight.
There are also massive changes to the gods of Olympus, mostly improving their abilities or changing how they work. Some had criticised the boons in Hades II as not being as powerful as those offered in the first game, and it seems Supergiant has taken that feedback and improved what's already there.
Check out the full patch notes here.