I'm one of these gamers that buys a lot of games, but tend not to finish many and plays only until the point at which I feel that I have gotten enough. I say this because Nier: Automata is one of the first games I have completed including endings A - E and has taken a spot in my favourite games of all time. I will try to use spoiler tags where possible, however, if you've not played yet, it is definitely worth going in blind.

Nier: Automata is a wonderful fusion of hack and slash mechanics, a beautifully emergent RPG and a bullet hell style shooter that plays with game mechanics throughout keeping gameplay fresh, interesting and intrinsically linked to the story.
One of the best trick this game pulls to keep you sucked in even from the early game is to seamlessly switch from a front scrolling ship shooter, to a twin stick shooter, into a fully 3D movement fighting arena to a sidescrolling fighting game. I mean, this all happens in the prologue and really sets you up for the kind of adventure you're going to be having throughout.
One you get a hang of the combat, it's well paced, feels very kinetic and the animations are beautifully fluid. This stands true throughout and is consistent across all the playable characters.
The one criticism I have is that sometimes, the combat is a little bit easy in the easier difficulties and downright punishing in the harder difficulties. On top of that there is an abundance of healing items to sustain you through so as long as you're not one-shot, then you're going to be ok.

When I say the art style and graphics are amazing, you better believe it! It's not the highest fidelity world you'll ever see in a video game, however. the design work that has gone into everything is a marvel to say thew least. There is nothing in this world that doesn't fit in and everything that exists seems to exist for a reason. The world constantly reshapes to the events that occur around it with you experiencing a different version of the game world in each segment of the game.

Oh. My. God.
The sound track is phenomenal! I have never gone out and bought a games soundtrack after having played the game before, but when I saw that barely any of it was on Spotify, I bought the whole thing. The music pumps the atmosphere of the game all the way up to 11. The director and sound designers had to know the game inside out and understand how the player would be feeling, as this is hands down one of the best synced up sound tracks I have ever heard. Even after having played the game, the music evokes an emotional response upon hearing it.
There are many great examples of where the music enhances the game going quiet and solemn at the right points to add poignancy to what you have just experienced. My favourite examples of which are during the fight with the opera singing robot and of course during the sequence leading up to ending E. For me the change in the music after you accept help where the single voice becomes a choir game me a shiver but throughout the music perfectly matches the tone.

Having said what I have said so far, this game goes from being what seems to be a simple plot to being so deep and conveying a great message through not only the major plot beats but through how you play the game and the decisions you choose to make.
There are many games where your decision affects the outcome of the game but one of the best parts of the decisions in Nier: Automata is that those decisions sometimes don't affect the game, they just affect the player and how you feel about what you have said or done.
I have chosen to delete my save so that I can play the game again from start to finish through a new lens as after completion revelations, you are definitely going to want to experience it again to gain new meaning to what you have seen.
Final words: Please buy this game and try it out. There are very few truly different games out there and this one is a masterpiece!