They are in for an unpleasant experience, as Malick's film is pure drama. In fact, the few battle scenes it does have are far between. The rest of the three-hour long film is up for viewer interpretation. As far as plot goes, it's indiscernible. What Malick seems to be saying is that there is no story in war.
War is about nothing in particular.
The closest thing that comes to a story is a chunk of the film dedicated to the storming of Guadalcanal. But it's not even really a story. The film is as disjointed as any this year, but where other films would crash and burn with this disjointedness, THE THIN RED LINE succeeds beyond expectations. War is disjointed. There is no beginning, middle, or end.