Just finished it and I absolutely loved it.
It wouldn't have hurt to trim an hour or so from the game. While it didn't outstay it's welcome for me, by the time the ending came around I was happy to finish up.
There were one or two sections that I could have done without. Usually anything with the Androids. More human encounters would have been nice.
There was altogether too much "Go here and turn on this thing. Now go over there and turn on that thing. Oh now go back to the first thing again"
I'm going to join the long list of people praising the atmosphere. It was just flawless. Everything felt like it belonged in that universe. I could picture the characters from the first movie existing in these places.
While my initial fear passed after around mission 6 the tension really came back in the last third of the game, especially as the
station is in the process of disintegrating around you! The
flashback to LV426 was tremendous, the discovery of
the nest under the reactor and then everything after
Ricardo gets facehugged was utterly brilliant. There were so many wee moments that just absolutely made this game for me. Alien is one of my favourite movies of all time, so without it I'd almost certainly never have played this (I'm a shitebag and hate scary games), but I'm so glad I have. This is definitely in contention for my GOTY.
The ending...
They've definitely left it open for a sequel. I'm not sure what they could do with it though as they've pretty much nailed it here and there's nothing more I can think of that the game would benefit from. Ideally I'd like to see some Campaign DLC that wraps up the loose ends, rather than another full game.
So yeah. Alien: Isolation