I honestly have nothing profounder to say about this novel (novelette?) than that I really, really like Ian McEwan's writing. It is so careful, precise, balanced, and yet emotionally evocative that I frequently must take breaks of a few moments from his novels just to let myself catch up to the lyrical beauty I've just taken in.
On Chesil Beach is, in my opinion, flawless; Jonathan Lethem points out this passage in his NYT review of the novel, but I think it's just a perfect encapsulation of how good McEwan is as a novelist on the most rudimentary level (i.e. show, don't tell):
Just before dawn he got up and went through to the sitting room and, standing behind his chair, scraped the solidified gravy from the meat and potatoes on his plate and ate them. After that, he emptied her plate — he did not care whose plate it was. Then he ate all the mints, and then the cheese.
Within the context of the novel's events and the character's state of mind, to eat the mints before the cheese says everything about the disorder, disorientation, and the nearness of revelry to revulsion that McEwan wishes to invest his character with, but in a throwaway, easily missed detail. It's glorious—simply read as much of McEwan as you can.