I liked this book but didn't love it. There's a certain style that some writers have when they write about New York City. It is, perhaps, their style even when they're not writing about New York. I wouldn't know since I only read one thing in that style then avoid the author afterwards. The word "sardonic" comes to mind, but that's not quite it. It's kind of an undercurrent of, "I know the different neighborhoods, I know the art, I know the fashion, so you know I'm cooler and more clever than you." I got the same thing from Don DeLillo and the one Norman Mailer book I attempted to read (although that one wasn't set in New York, it had a similar style). 
 I agree with my friend Lauren that Cunningham's descriptions of people are largely satisfying, but he relies a lot on dropping the name of the designer of the person's boots or scarf or whatever to illustrate something about the person's character. On the one hand, I think this says something about the shallowness and appearance-consciousness of the main character. On the other, as someone who recognized only Prada and Tony Lama among the dozens of designer/brand names in the book, I think I missed some of what he was trying to say about his characters. He does a similar thing with references to artists and works of art. I don't even know if the artists he mentions are real or fictional. I'm guessing it's a combination of the two, but I couldn't tell you which were which. 
 Reading a book like this is kind of like sitting at a dinner party filled with people who know each other who, rather than inviting me into the conversation, persist in speaking only in private jokes that are meant to impress me but merely confuse and exclude me. I get it, I want to say. You're clever. Now can I just eat my dessert and go home? 
 By Nightfall wasn't as bad as that for me. I enjoyed the gradual unraveling of the main character and his view of the world. I grew to admire the Carole Potter character, and felt I got a good sense of her and her home, despite the fact that I had to gloss over the drawn-out description of every piece of art in her foyer and living room.