Completed it a couple of times, here are my bullet points:
1. It's hard to be scared of something nibbling at your ankles. Get those Aliens stood up and menacing!
2. In my opinion the Lighting Methodology is all wrong. There is too much use of darkness as a gameplay factor in my opinion and it wrecks the game.
3. The torch. Sucks ass. In my opinion they should either make it less effective but give it more longevity, or else increase the effectiveness and keep the Battery system.
4. The flares. Both suck AND blow. Either make them inexhaustible like the AVP1 flares, or just make them more effective, please.
5. There was an art choice to go with later film type aliens, rather than the Aliens movie aliens. I guess that's valid if you like that sort of thing but, for the record, I prefer the more bio-mechanical aliens to the more organic later film ones.
Last but not least, my condolences to Rebellion - I'm pretty sure the short sighted decision to go with Monolith will badly affect the quality of the final game.