It's clear from other reviews that more or less everybody is agreed about the director's rather tricksy film-making and the lack of conventional narrative drive. It's just a question of whether you think these things make for a good film or a bad film.
For me, the good outweighs the bad: the deliberately non-emotional characterization, slow pace, and powerful use of landscape push viewers out of their comfort zone, and force us to confront some pretty basic realities about life and war.
It's the parallels - not the contrasts - between home life and the war that are most interesting. On many occasions, the film seems to have a deliberately timeless, ahistorical feel, so that the characters feel tremendously elemental (the word medieval springs to mind too) in their behaviours and concerns. Despite a slight lack of coherence (not necessarily in the plot, more in the overall conception), we do genuinely somehow care for the characters - quite an achievement given the overall tone of the movie.
The use of Flanders as the setting and title reinforces this sense of historical continuity, of war recurring down through the ages - not for nothing is the region known as "the cockpit of Europe". And by the way, a big chunk of historical Flanders is now in France (the French-plated cars, with "59" indicating the North department which includes most of French Flanders, are a giveaway). French Flanders is by definition not in Belgium, as one reviewer has suggested. However, one of the female characters (Barbe's friend) appears to have a strong Flemish (i.e. Dutch-speaking) accent - a nice touch, and not entirely implausible in this border region, where a few people still speak Flemish on the French side of the border (visit Hondschoote, and you'll see what I mean).
This film should make everybody rethink their approach to war, and the impact of sending young men (and women, although not in this film) from more or less every generation off to fight and die (remember that Flanders was scarred by war twice in a lifetime in the 20th century). Not necessarily a particularly easy watch on the face of it, but a powerful and worthwhile one.