I played it on normal and died. Alot.
The game still fascinates me although I've finished it in December. There's just something about it that still sends chills down my spine. It is very well executed and everything you love from the first Alien movie is definitely there. The use of music is just masterfully handled (though it of course might cause a few unnecessary jump scares later in the game while nothing happens) and the whole design is stellar. The look of this game cannot possibly be better. It's a true work of art IMHO when it comes to sci-fi games and beats Dead Space out of the water for me personally. While Dead Space looked more like Alien3 which I also love because this particular visual style.
My only gripes with Isolation being that it may be a bit too long, while the story itself is not all that suspensefull through out the game and that you barely get to see other survivors compared to the vast size of the Sevastapol station. A bit more live could have helped the atmosphere since the interactions between the NPCs and the Alien are rather clunky at times.
The re-play factor is relatively low aswell, but that's mostly because the whole journey is relatively straight forward. You probably won't find an easier way or a more probabale solution to problems you encountered in your first play through. And it's just too long in the end for me to play through it. You actually will have to find time, turn off the lights and engage that game once again rather than just aim for a quick session.
I guess most negative reviews stem from the already mentioned difficulty some players may have with the gameplay itself. It IS a survival horror game and not a shooter by any means and therefore your whole playing style is totaly different. There are a ALOT of passages where you just have to be patient and wait. It's like playing a FPS where you will die when a single bullet hits you and you actually HAVE to take cover and behave like it's real warfare around you. I dig games like Red Orchestra because of that very aspect!
Another reason might be that after so many let downs in the Alien games franchise and with Prometheus (which I fairly liked BTW but was a missed opportunity nevertheless) people's expectations were unrealistically high to begin with. There just is nothing left to explore. We all know what the scenery for these games look like, we all know what the Alien looks like and what its story is, we have seen the movies to death. But come to think of it: has the Alien itself ever been so perfectly visualized in a game? Has the atmosphere of the first movie ever been captured? No! And this is what Alien: Isolation does to near, and I explicitly say, near perfection! The game has it's flaws like any entertainement but it's pretty much my favorite game of all time because it's finally challenging, has great graphics, an unusual gameplay and yes, my favorite movie franchise aswell.
It just has this undeserving spot in history where the franchise has been beaten to death. It's a dead horse but Isolation revived that horse for me fairly well.
Spoiler: While it was a extremely short sequence, I had a HUUUUGE blast entering the Derelict Space Ship! A really fantastic nod to the franchise!