I just finished it. It really is a long game! I still loved every single second of it.
Honestly, as a sci-fi fan, I find it hard to be too critical of this game. These guys wanted to recreate the atmosphere of the first Alien in a different setting and they nailed it. Yes when you look at from a critical standpoint; the gameplay is mostly traversing areas, hiding, pulling levers and triggering cutscenes. The combat is simple and most of the time you don't have a chance anyway. Most of the inventory is useless even at hard and the combat is usually very spontaneous so using them to make traps is just wishful thinking.
However I don't think amazing gameplay mechanics are the point of this game. It's the experience. The graphics, the sound and the art meld so beautifully that if you enjoyed the Alien franchise, it's very hard to stop playing it. It's sci-fi porn at its best. I actually rewatched Alien today and I'm amazed by how much the game resembled it and captured its ambience. The level design needs a mention as well. It's incredibly detailed and atmospheric (the lighting especially) and keeps its quality throughout the game. It doesn't stay the same as well. You actually see the station go from its pristine condition when you arrive to absolute wreckage towards the end. Same for the sounds; I don't think I played a game before where sounds were so well made. From the meaty footsteps of the Alien to the beeps and boops of the computers it makes the whole experience so gripping. I also loved how they used complete silence sometimes as well.
I think the closest game you can compare it to is Amnesia. You are at the bottom of the food chain in this game. When an Alien notices you, you're fucked. When a human notices you while you're sneaking around and starts making noises, you're fucked (because the Alien will show up). Androids show up when you're not ready, you're fucked. So you sneak and try to find alternative routes instead. You'll die a few times trying it, but eventually you'll find the right combination of timing and chance. It's so satisfying in the end.
Overall, this was fucking amazing. It's definitely not for the fain hearted though. The tension is always there and then there are the jumpcare moments . . .