Most war movies involve actual wars but with dramati license...is that your issue with it?
I like it for reasons totally separated from the war setting. I like it because it seems to me it's about a junkie who's found his drug, and what happens to him when he loses control of that, and what happens to him when he goes home. The scene in the grocery store, and what followed, was actually my favorite part of the movie.
Well, and I'd be silly to deny that also, it was crazy intense and the direction was stunning. It's like somebody said; a movie with only three explosions can be way more heart-pounding than a movie with 50 explosions.
EDIT: I also like the senselessness and futility that the movie illustrates by introducing a number of characters (at least three) who die more or less immediately.
The plot points that go nowhere, too, seem like a confirmation that, hey, in life sometimes a plot goes nowhere too, and in real life you can end up confused and frustrated and caught in a tangle yourself.