Very under-rated game that is as engrossing and submerging as they come!
Why does it get so much love? I think mostly because the game is very immersive. If you play this game with the lights off without any distractions you are going to totally get immersed into its world. It has very nice graphics, particularly the environments, the music and sound effects are down-right nerve-tingling, and the story is very good (what the hell is the gamespot reviewer talking about). It takes a lot for a game to get me hooked and this game did just that. My biggest criticism is that the enemies were too similar. There weren't many different types, and many would look exactly the same. For a game that is so immersive, it definitely hurts the believability of the world when you see the same enemy character model over and over.
It might also be too short for some with just 10 levels, but for me personally it was of decent length, I don't like long games (because I never finish them).
Overall, this is a great game, and is something that needs to be experienced by all 360 (or PC owners). It has good graphics, good audio, a great story, and is quite addictive. It doesn't have much replay value, but it does have some stuff to collect in each level (birds & metal plates) so it has some replay value. I got this game for $18 dollars at gamestop/ebgames, I am happy with my purchase, but if you prefer you can also rent this game as it's definitely doable in a couple of days.