And yet, it really isn't.
It's still a third-person cover based military shooter, and is so inoffensively run of the mill, it doesn't do anything to make itself stand out. The set pieces and environments are mostly forgettable (you see one opulent hotel lobby filled with sand, you've seen them all), and the main characters are so bland they're not really paying attention to. Yes, you can say that the story is good, which of course it will be as it's based on Heart of Darkness. But even then it's implementation is only average at best, relying a lot on audio logs to tell the backstory. The fact that all these critics seem to falling over each other attempting to praise the game for its narrative only goes to show how poorly narrative and story are treated in games.
If you've got £30 to burn, and need 6-8 hours of entertainment (don't bother with the multiplayer), you could do worse. But other than that I wouldn't bother.
You're perfectly entitled to your opinion, but I'd swear we were playing different games. First of all, sand-devasted Dubai at sunset is FUCKING BEAUTIFUL. I swear, the vistas looked like a post apocalyptic Mirror's Edge.

Also, I don't know where you're coming from with the characters- even if they sounded like your standard hardened-yet-goofy patriot squad at the beginning, there's some strong development with them as the game continues.
But as for the backstory, were you even paying attention at all? I only picked up about 4 or 5 audio logs throughout the whole game, and I still managed to perfectly understand the motivation behind the characters and their relationships through dialogue and actions alone. And even then, the audio logs I found were more supplementary than expository, being things like poems left behind by the antagonist or a reading of the code of conduct for the enemy soldiers Hell, Dead Space relied more on audio logs for its story than this and it tells its plot perfectly well enough without them.
And yes, by being based largely on Heart of Darkness, it's not a perfectly original story, but I do think that being a game made a major difference in how it was conveyed that it couldn't have had in any other medium. The events behind the "game changing" event occur organically within the mechanics of the game and with the total consent of the players action as opposed to preemptive menus and narration; it's not even like the airport scene in MW2 where you're assigned that mission in advance by a higher authority and even then are free to walk around without killing anyone. In The Line, it comes off as a choice you make YOURSELF by simply playing along with the rules of normal shooter game conduct. In fact, I'd be curious to see if the story would have had the same impact if it DIDN'T play out like a generic Gears clone, because I imagine its ability to deconstruct war games is dependent on it playing like one.