Tl;Dr: Great game, highly recommend it.
Gamplay: 7/10
Sound Design: 10/10
Visual: 10/10
Level Design: 8/10
Immersion and Story: 10/10

The true review:
This, is, an amazing game. It is a masterpiece in its unique approach to interactive design, and it provides a story that is heartfelt and relatable. Hellblade: Senua's Sacrifice takes you, step-by-step, through a journey that allows understanding of two difficult subjects: Death, and Mental Disease. By the end, you are left with unanswered questions, but at the same time with the hope that you, the player, will be able to answer them. Not for Senua's sake, but for yours.

Gameplay - 7/10. Combat is simple and approachable, nothing out of the ordinary. It is simplistic enough that you can easily go through the game without dying a single time, but at the same time allows for self-discovery to employ that simplicity in new and interesting ways. At the same time, the ways that you employ Focus (an in-game mechanic) allows the player to solve puzzles and to see the world in new and different ways.

Sound Design - 10/10. I say Sound Design and not just soundtrack because the latter doesn't make the whole game. Yes, what little music and ambient soundtrack there is in the game is top-notch, if a bit repetitive, but it is the way that Senua's Psychosis manifests itself in the game that truly shines. The Voices are a constant companion, a helpful cacophony that ensures you will never feel alone, nor will you ever lack for help in this journey. It is also the presence of the Voices that makes you realize that the repetitiveness of the soundtracks is made on purpose; this is all made to draw the player in, and invest you into trusting not what you see, but what your mind tells you to trust in.

Visual - 10/10. The Unreal Engine is puts to its full use in this masterpiece, presenting you with amazing landscapes and striking locations that will forever stick in your mind. Your journey to Helheim is filled with locations that have been twisted by Senua's psychosis, and the game truly delivers in presenting the fear of what you see, of trusting not in your eyes, but in your mind. And then of course are the puzzles themselves - while it is the player who solves through them, the game presents them in a way that doesn't make them unsolveable, but that will require you to think outside the box.

Level design - 8/10. I'd give it a 6 if not for the puzzles presented for you to advance throughout the game. Each level is pretty straightforward in how you get from point A to D, but it is the puzzles in B and C that leave you with your head scratching. You are required to think outside the box, to look at the world that is hidden with illusions and shadows, to bring shapes into existence that simply should not be there to begin with but that with the player's well-placed thoughts will allow you to progress.

Immersion and Story - 10/10. You will be invested. You will be brought in. You will find yourself fearing death. You will feel your heart break when you reach the ending. This is a story that brings tears to your eyes. This is a story of death. This is a story of heart break. This is a story of darkness nipping at your heels, and of the strength to grow beyond the shadows of the past.

And when the Voices are silent, you will find yourself missing them.