If the primary goal of writers was to look cool, the French literati would win hands down. (Except for Sartre, he just looked weird.) Albert Camus with his perpetual smile and cigarette; Honore de Balzac with his Bohemian appeal; Victor Hugo with his perpetual grumpiness. It's as if they're all posing at all times, in case the adoring public is around the corner to catch a glimpse.
Fortunately for the reading public, most of them had a good handle on content, too. Sometimes too much: you hear about the interminable length of Russian novels a lot, but many of the French classics are just as long, and just as difficult to slog through. Alexander Dumas stretched compact plots over the course of thousands of pages; Marcel Proust apparently had the world's most spacious and detailed memory, and he was unafraid to share it in its entirety; Victor Hugo goes on and on about events not pertinent to the novels they appear in (perhaps the source of his grumpiness).
Like the Russians, French writers are seemingly incapable of separating their stories from the weightiest matters of existence, love and sex, and the ever-present spectre of Death. This isn't a bad thing, though—it simply makes for better literature than the vapid adventure stories and romances that fill the bookstore shelves these days (Exodus Books being the exception, of course). It also makes for literature that takes some effort to read.
Even a writer like Dumas, noted for his rousing action and intrigue tales of 17th century roustabouts, frequently falls into a meditative mood. His greatest work, The Count of Monte Christo, is a long essay on human evil, the selfishness of many inherently "good" acts, and the nature of divine and human justice. If you're looking for no more than swordfights and chases, don't look here; you'll find them, but plenty else besides.
The "plenty else besides" being the really good part of literature. In our 21st-century American milieu, we've forgotten that two-dimensional presentations of three-dimensional objects are boring; action for its own sake, romance as an end in itself, mysteries that make no comment on the depths of human nature are really of no interest except to pass some idle time. Great literature is fascinating because it forces us to reflect on life, on the major questions that we too-often neglect.
French literature is mostly of the latter kind. There's a curious intersection among its genres that makes some readers uncomfortable, a willingness of philosophers to write novels and plays, and a tendency for novelists to philosophize at will. In fact, it's this elasticity that makes French literature so much fun to read; you don't know when you'll be confronted with the difficult questions of life, the universe and everything, but when you do they'll be sure to make in impact.
Of course, many of the answers French writers supply are just plain wrong. Along with Germany, France was the birthplace of the Enlightenment, and the intellectuals of the country never fully recovered. Most of them are atheistic humanists, existentialists, nihilists with no moral framework or real sense of direction. They respond to what they see and experience, and they respond only as men and women without God can.
Yet France was also formerly a bastion of the Catholic Church, and her thinkers haven't been able entirely to shed that memory, either. Voltaire was a posterchild for the rationalist Enlightenment revolution, but he was preoccuppied by Christianity and its tenets. In the 20th-century, the existentialist for the ages, Monsieur Albert Camus, went back to the Church time and again for inspiration and creative fodder.
If any one idea can be said to have dominated French literature, it's the idea of existence. If this sounds fairly vague and broad, it is; but the particular interest the French have taken in the idea of human existence is how meaning may or may not be made out of the seemingly incoherent mass of desires and actions of which it is comprised. This is the crux of existentialism: if God isn't in the picture, man is responsible for making his own meaning, and he does this through a series of attempts, each of which supercedes those that came before.
Postmodernism, the natural child of existentialism, goes further. Also born in France and espoused by men like Michel Foucault and Jacques Derrida, it claims the non-existence of the individual, that every person and every society is simply the construct of millions of outside influences. Whereas existentialists claim "existence precedes essence" (meaning that human nature is not universal, but constructed by each individual on their own), postmodernists essentially say that essence is existence.
Human nature, then, is simply an invention; by extension, humans themselves aren't particularly valuable, except as conduits of pleasure or means to ends. The modernist liberal insistence that everyone is valuable and important (not the same thing as the biblical idea that man is created in God's image) rings false in a postmodern context because there is no grounds for supposing humanity is something to be cherished or preserved.
This has not stopped both existential and postmodern writers from defending the rights of humans. Perhaps the great irony of those philosophies is that philosophical frameworks inherently betray a concern for humanity, and neither existentialism nor postmodernism are exceptions. The French love is for life, and her poets, novelists, essayists, philosophers, and dramatists demonstrate their fascination whenever they put pen to paper. If they're inconsistant at times, who can blame them? The passion that emerges from their writing is both a stabilizing and destabilizing force in their vibrant and virulent literature.