So this is 'magic realism'. I'd always recoiled from the phrase, not expecting to find much to enjoy within the genre (though I've enjoyed what Borges I've read, if he counts), but my expectations were, to some extent, upended by One Hundred Years of Solitude. To begin with, I didn't expect it to be so strongly grounded in social reality, and in political concerns. And for seconds, I didn't anticipate that the 'magic' or fantastic elements would so effectively serve literary purposes - the way in which the returns of dead people, instantiated through their ghosts, serves as a literalisation of the underlying theme of the ongoing dialogue between past and present, for example.
The sense of the endless repetition (which I'm not entirely sure is repetition with difference) and circularity of history is what I most clearly took away from the novel. The theme is made explicit at several points, as Úrsula in particular remarks on it, crossing over and mixing with the sense that history, literature and reality are separated by boundaries that are inherently permeable, which complicates the historically deterministic flavour of that emphasis. I wasn't sure what to make of the ending - will need to think more on it, but initial impression is that the idea of deciphering the image that one is living is at least potentially a transformative rather than conservative one.
A less critical response: I liked the book without loving it - and you have to admire its verve and what seems to be a real accomplishment.