For starters: It's a best game of 2014 for me.
Things I would change:
1. I agree - noise of coming out or hiding in the lockers. It is stupid actually. You are sneaky little sneak and then... WHAM!
2. Add eggmorphing to the story instaed of presumed queen.
3. Add an option for removing the "invisible leash" between you and alien so it can really venture acros the entire map. It felt little cheap that it always knew the area you were in.
4. Remove the cliffhanger ending (finish the story properly and definetly). You can always come up with the new one for the sequel - be it with Amanda or not. Additionally maybe different endings depending on players actions..?
5. Add more death animations. There are like what? Four of them? Chewing your face, tail through the back, vent grab and Joe snapping your neck. How about waking up in the nest to give birth to the chestburster or being morphed into an egg?
6. Add a "silent mode" to the xeno. The one that will shut down all the growling and barking it does all the time. Standing still in the shadowed corner of the room, hiding between pipes resembling its appearence or sitting still on the ceiling. You get my meaning - the Narcissus scene.
7. And most important: CREATIVE ASSEMBLY! HURRY UP WITH THE SEQUEL