I picked up this book because of the rather extravagant praise from Borges and Paz. Apparently it was inspired by the silent film star Louise Brooks, which makes sense: the entire book is about our capacity to love phantoms. All of us probably remember early infatuations with celebrities who never existed for us as anything but reproductions: on paper, televisions, the movie screen.
Essentially, this book imagines what happens when the reproductions become faithful enough to be indistinguishable from the real thing. It is narrated by a man hiding from the police on a deserted island for an undisclosed crime. One day people appear, and the man quickly falls in love with one of the women; strangely enough, they often disappear for short stretches of time, and seem to repeat the same conversations and actions again and again.
All of this is well-written, but when the explanation is given, all that preceded seems to have been time spent waiting for the a-ha twist: it's only after this point that the book becomes really interesting. I won't give away the story, because the plot is worth getting through yourself: let me mention something that it reminded me of, though.
When Apocalypse Now: Redux came out, they restored scenes of Martin Sheen's brief love affair with a French woman on the river, a storyline completely left out of the original cut. The actress, now an old woman, went to the theatres and saw herself young and beautiful again. And something about her youth is now eternal, or at least as eternal as film proves to be.
I find it completely plausible, for example, that one could find a bundle of old home videos and be so charmed by a woman in them (since I'm a man) that you fall in (some sort of) love with her, even though she is probably either dead now or a completely different woman. But in some way the image of her is real, in the sense that it exists on the tapes and in your own head.
These are some of the ideas that this book plays with and, I must say, it is more fascinating for the ideas it provokes than the narrative itself. In many ways, it feels like second-rate Borges: The Circular Ruins (or a few other stories) stretched to novella length. What Casares should have accomplished with this length is given Faustine (the woman) some sort of character that seemed worthy of the reader's love, and not just the narrator's. At the moment she's a non-entity.
So this story isn't heartbreaking, as the other reviewer (whose flimsy review, frankly, shows no evidence that he actually read the book) tries to say. The Invention of Morel is the work of a talented but not brilliant writer. Perhaps another flaw of this book is that the ideal medium for the story seems to be film; I can see why this was, supposedly, the inspiration for Last Year at Marienbad.
In any case, if these ideas strike you as interesting, I recommend this book. It's really very short, and perhaps not worth paying this much for, since I wouldn't care to have it as part of my permanent collection; I read it first in the library, where it had several short stories from Bioy (NYRB might have included those) as well as several lovely woodcut illustrations.