Terrence Malick's work is sadly not-oft appreciated, as he's only made four feature films. The Thin Red Line definitely goes down as one of the greatest films of 1998, possibly one of the best of the 1990s.
Where Black Hawk Down and Saving Private Ryan don't spend much time exploring, The Thin Red Line goes right into it, everything from God to finding courage. Sure Malick can direct some pretty awesome action sequences, but he can also explore these topics in between those enthralling sequences of chaos. Thematically, this is probably the best war film since The Deer Hunter. I should mention the score by Hans Zimmer is also worth noting.
I'll also mention that one shouldn't expect a single outstanding performance or a single character to get to know real well. Everyone really takes a back seat to Malick's ethereal style of direction, filled with visual thoughts and imaginings combined with serene shots of nature, in between some finely directed firefights, of course.
What really caught my attention was the reason for the name of the film itself. Watch for The Thin Red Line that appears on a blade of grass when someone gets shot or The Thin Red Line that flows down from the wound in a soldier's cheek.