The devs made a post on Steam to that effect. Beyond that, the devs says that they are investigating reports of the issues with Horizon Zero Dawn on PC, and it will be their highest priority.
Beyond that thought, the devs at Guerrilla did not provide much in terms of details. There’s no indication of what exactly is the problem just yet. Naturally, they’ve also not shared when we can expect a fix. All that was said was that they “will update you all as soon as we have more news”. Because of the issues, Horizon Zero Dawn is now with a “Mixed” review rating on Steam. So whether or not you’ll experience issues is really a coin flip. If you have a system that can run the game, then it’s probably worth the gamble. And even if you’re not the gambling type, it’s unlikely that Guerrilla Games will leave the game unfixed, unlike WB Games and Batman Arkham Knight. (Source: Steam [1], [2])
