Julian Young's Heidegger's Philosophy of Art is pretty helpful in extrapolating philosopher Martin Heidegger's philosophy of art. Its best explication is the first part, which involves a close reading of Heidegger's infamous essay, "The Origin of the Work of Art," in which, Young argues, Heidegger pushes a thesis similar to Hegel's.
Basically, Heidegger's contention is that great art is a thing of the past, but artists might one day be able to inaugurate a new generation of great art. Great art is the kind of artwork that draws people together. We see it embodied in, say, Homer, which defined what it meant for the Greeks to be Greek. We also see it in Michelangelo's frescos in the Sistine Chapel, which drew Europeans of the High Renaissance together in their understanding in relation to God.
But in contrast to previous epochs, Heidegger thinks there's no work of art today that could draw us all together, and that's because of our relationship to technology, which has desacralized, he believes, our relationship with nature and each other. Of course, Heidegger's not wrong about the exploitative nature of modern times, but a better diagnostician would have said the problem was capitalism. If only Heidegger could have drawn upon some German precursor who had diagnosed the trouble with our material conditions...
Anyway, Young's explication of Heidegger's essay is very good, but I find parts two and three of this book, which try to show the changes in Heidegger's thinking vis-à-vis Heidegger's writings on Friedrich Holderlin to be less convincing. Although—whatever—I do buy that in Heidegger's later period, he became more optimistic about social possibilities and the possibilities for great art.
Read this if you read Heidegger's "Origin of the Work of Art" and it doesn't make sense to you.