Currently playing on PC. Havent come across any of these 'issues' the reviews are talking about and have played SP for a good solid 3-4 hours so far. Poor AI? Playing on hardened difficulty I had a few groups of Aliens slip into corridores next to me to flank my position and have them always keeping me on my guard, in the open areas they swarm at me and are easy to kill but I did have a few good scares in the first few missions (havent finished the campaign yet only about half way through).
Graphically, the game looks fine to me. Maxed out settings on the PC and it looks great, at least as good as any other shooter out there that I have played, a few things look a little dated but overall no complaints.
Story wise, yeah it could be better but it still has me hooked. As a die hard fan of anything Aliens, I am enjoying the game. Maybe its just me that doesn't like to waste my time bitching about things in general but I don't know why so many people are ripping this game to shreads. I have played games much much more worse that have received higher review scores than this game.
Overall a solid 7/10 from me - Its not the greatest game in the world but it does have its moments. Love the little easter egg references from the movies
Spoiler
Finding Newts lost doll head in the sewer was a cool touch