Whilst this is by no means a masterpiece in gaming, ala Halo or COD, this game manages to pull off being fantastic fun without taking itself to seriously. Fans of the Alien movies will get the greatest amount of joy out of this game, with all the best bits from the Alien trilogy referenced or paid homage too. The Pulse Rifle cackles with comforting familiarity and the scream from an Alien as you reduce it too a pile of acid will do all to well to remind you of Aliens (the movie). The Predator takes somewhat of a backseat to the war between the humans and the Aliens, but that is not to say their part is underplayed. You will have great fun playing as any of the 3 species, it really doesn't matter who you choose. However, it should be noted that I would only recommend this game for those with online play. The 3 campaigns are good, but are quite short, and therefore are only recommended by their own merit for the most hardcore of fans.
Multiplayer will be where you find yourself spending the bulk of your time, the most enjoyable modes being "Survival", "Infestation" and "Mixed Species Team Deathmatch". These 3 modes will most definitely keep you playing this game beyond the purchase of your next title, and that's before you even touch on the other 5 multiplayer modes.
The only negative I can give this game is that it is most definitely one for the fans. I love it so much because I am one of those fans. However, if you are buying this game with no prior knowledge to the Alien or Predator universe's, then I think you may find yourself a bit confused and lost at some points. In conclusion, if you are not up on Alien or Predator lore, then I would only give this 3 stars, and recommend you rent this game first.
P.S. And just on a quick side-note, alot of people seem to be knocking this game because it bears some resemblance to the average Alien Vs Predator movies, but it should be noted that the AVP games on the PC outlined these storylines years ago, and it is actually the films which ripped-off the games, not the other way around!