Guerrilla Games has updated Horizon Zero Dawn recently with a new patch and along with some of the bug fixes, they have also improved the water shaders. The issue with the water rendering in Horizon was more along the line of how it reacted to the character. The reaction was rather tame and far from the impressive tech that most other open world games seem to utilize in their engine. The water shaders have now been tweaked in an update so the water reacts more to Aloy which should help alleviate some of the original complaints.
The two animated GIFs below were taken from a patched and unpatched version of the game. The difference is clearly visible as the water reaction to Aloy was almost non-existent in the pre-patch version even though she clearly did dip in the water. It breaks immersion of the open world to some extent so it is nice to see this finally fixed.
Horizon Zero Dawn is the first open world action RPG from Guerrilla Games. It is also getting its first story expansion called The Frozen Wilds. This story expansion is reportedly 15 hours in length and adds new monsters, weapons and a brand new location to the game. It can be purchased for $19.99 and it comes as part of the Complete Edition of the game.