I played for about two hours and I'm enjoying it.
I don't find very many horror games to be scary. The Fatal Frame games are the scariest games I have ever played. P.T. was pretty damn creepy. Daylight was creepy because the sound was so great. I absolutely love The Last of US, but I didn't think it was scary except for a little bit in a section later on in the game.
Alien Isolation wasn't scary for me, but it was very tense. The Alien is extremely intimidating. It's very smart, ridiculously fast, and it's basically immortal. You feel so fucked when you're in a small room and it comes in. Maneuvering around/under tables while trying to stay out of its line of sight is a rush. Throwing a flare to distract it and then sneaking into a vent to get away is a blast. But it's not scary for me. Some people found the androids to be very scary, but others thought they were dumb. I liked them, but I didn't find them scary. There were a few times I found them intimidating though, especially when they were in large numbers. They can be killed, but they are very tough. I got adrenaline rushes slowly creepy through a hall, which is unusual for me. I think Alien Isolation is much more tense than The Last of US, but I don't know what scares you, so I don't know if you'll find it scary. Both games are fantastic.