The Waxman Literary Agency blog explains this idea here -- essentially it's the same idea referenced in my last post, of being able to sum something up in a sentence or two so that it sounds catchy.
Haruki Murakami's A Wild Sheep Chase probably doesn't exemplify high concept, since when I recommend it, I often find myself saying, "I won't tell you anything about the plot, because then you'll just think it's some weird book only I would like. But just take my word for it, you just have to read it!" Back when I used to try and explain the plot, people just stared at me in bafflement. Not a problem for Murakami -- he'd acquired a devoted celebrity following long before he wrote this masterpiece, and didn't need me on his sales force.
A book I like that might actually be high concept is Jo Walton's Tooth and Claw. This is the only novel I can think of that, when I insist people read it, I actually quote from the blurb: "A Victorian novel of manners in which all the characters are dragons and eat each other." I guess if you quote from the blurb to get people to read something, it must be high concept?
Books in the first category may ultimately be more rewarding to reread. But since it's axiomatic that books sell by word of mouth, publishers will understandably tend to prefer books that are easily promotable by word of mouth. Hence, if you're an unknown author, trying to get publishers to take a look at a book in the second category is less likely to turn all your hair grey.
But as the Grateful Dead would have it, "Oh Well, a Touch of Grey Kind of Suits You Anyway." The obvious defect of the high concept approach is that it leads to a proliferation of nonbooks, having hardly anything to recommend them beyond the premise's initial gimmick.
A guy I met a few weeks back told me that, in his experience, really successful people tend to be people who are doing what they genuinely want to be doing. This man wasn't a writer, but he had perceptive things to say about Robert Frost and Alice Munro -- maybe his thoughts on life were perceptive too. As against which, I would have to add that really unsuccessful people also tend to be people who are doing what they genuinely want to be doing. Unless doing what you genuinely want to be doing is a kind of success in and of itself?