I have only completed a few games - in fact, you could count them on your two hands. This is not because I seldom play video games, rather because I'm not one to lose time in something I do not enjoy, and I leave many games mid-run.
You must know that I did not own a PS4 before 2/3/2017, and I got it specifically to play this game, which I was super-hyped for. It did not let me down: the main thing I always look for in any experience I throw myself into is the story, and, boy, did this one suck me inside! I will avoid spoilers, but know this: the way the protagonist is introduced to you immediately stimulates your empathy, and everything that follows feels very natural and a very "personal" experience. In fact, it all starts as a "personal" quest for Aloy, which will evolve, going deeper in the mysteries this future holds. But it will never lose sight of Aloy's quest, and this is a thing I want people who play it to notice throughout the story.
The gameplay is extremely fluid, and I got the grip on the controls after maybe 2 hours of gameplay (keep in mind that I had not touched a console in years before Horizon). The combat interactions are amazing, it would be hard to think of many other features or details to make it feel more "realistic". The possibilities are many and many when fighting a Machine or a Herd, and I think the gameplay is what kept me playing for an entire month almost daily: the (main) story does not take this long to be completed, but you can enjoy just being in this open world, taking dozens of different challenges, following the personal affairs of many and many - very charismatic - side characters.
About the graphics I can not add anything useful to what has been said by people who have played many recent games (which I have not done). I will just say that the last game which graphics really excited me was Xenoblade Chronicles, because of its beautiful and extravagant locations. The locations in Horizon Zero Dawn, on the other hand, were very earthly, with not many "alien" features popping up in the environment; despite that, the world felt idyllic (photo mode will totally convince you on the beauty of the game), at peace with itself, and "in balance". Sure, this balance is very fragile, and on the verge of collapse, as any story would require, but nonetheless everything feels "right".
Technical comment: I think the graphic engine is what makes the magic in terms of gameplay and graphics both. In fact there are very few texture bugs, and the character movement and interaction with environment is extremely fluid and natural. And obviously a beautiful world is no good if it does not feel real.
