well i've played it and finished it so i will give my imput. i had preordered if for around $30 from greenmangaming which was all i was willing to get out of it under best circumstances in my view and with my disappointment with dead space 2 and wanting some sci-fi i went with this. plus aliens, which i saw before alien, was one of the most memorable and scary movies that came out when i was a kid. so really i was looking for a bit more of that experience and also i had watched some of the multi gameplay videos and thought that had promise.
the single player is indeed underwhelming, not terrible just very meh, with the un advanced ai and not enough suspense and fear in the game. the guns are great though and the pacing in the game is right. short at around 6 hours, its still i'd say worth it for a fan of the series needing more of fix. clearly not for a purist and their are indeed far better games in the genre. i'd say wait 'til its $10-15 if you only want the single player experience.
what i really think is enjoyable though is the mutliplayer, and if it continues to grow, mainly with additions of new maps then there is a decent value in the game at a higher price. played about 8 hours of multi and that indeed does capture the feeling of aliens in my view. especially the survival and escape modes which are 4 vs. 4. playing the aliens takes a bit getting used to and in my view not as fun as playing as the marines, still what is nice is that you play as one side and then the other in each mode.
i'm not sure if the two people above played multiplayer as i'm not sure if that's available to illegal versions which are most likely the ones played but multi is definately where the value is. and not to digress but as much as pirates cause us more drm and higher prices, i'd say the opinions of "anchor gamers" dilute objective discussions on a games merit which may be the worse crime. what i find really perplexing is people who have the money/job and still pirate. they shouldn't be shocked though when the layoff karma police cornhole them someday.