Forget what you think this game may be and forget the kind of game you expect Ninja Theory would make, this isn't that game, it's something different.
Right off the bat this is a gorgeous looking game, Senua is maybe the most visually impressive character I've ever seen and the world was impressively grim.
The game put a lot of pressure on the player from the start, Senua is afflicted with an infection that spreads each time she dies and if it reaches her head it's game over, this made every encounter fell like it had very high stakes. Whenever I would die I would be in a full on rage and when I was successful it was that much sweeter; it worked but I hope this doesn't catch on.
The combat started out very frustrating but as I learned the enemy's tricks it became fairly easy, they keep sending new and more enemies through the whole game which keeps it challenging.
I thought the puzzles were really fantastic in this game, a good variety and lots of them.
The Norse mythology was cool, I thought it was funny that they very specifically never mention Thor yet hit most of the other Norse gods and creatures are well represented.
I didn't think the game was scary at all it was very much about psychological primal fear and it just didn't work on me, I think the hectic combat just kept me pumped for most of the game so when a "scary" part happened I was already raging and it just didn't work.
About the whole mental illness thing, I didn't get it, I played with headphone and the voices in your head was an interesting effect, it wasn't enough and it really made all the hype about it pre release feel like a marketing stunt and not some "we are a progressive game developer" bs they were trying to go for.
I think the game was a good length there's no filler it's goes at a pretty good pace and there is plenty to see and do.
I had one complete game crash and one spot where I got stuck in the world and had to restart.
Well worth experiencing.