To my surprise, I'm getting caught up in City on Fire. How did he do it?

Ok call me a liar but to my complete surprise I am now caught up in Garth Risk Hallberg's 900+-page novel City on Fire. In yesterday's post I said I was just dropping into this copious novel for a quick visit, that I didn't have any strong feelings for the characters, and that I could not imagine devoting the time to a novel of this length unless it was on the scope of other literary monuments such as Bleak House or Anna Karenina. Well GRH doesn't rise t that heights, but moving through the first 150 pages or so I have to say he does know how to get an engaging plot under way, his prose is always smart and clear, with some terrific passages of description and turns of phrase (and some real show-off vocabulary for better or worse) and, though I have no great sympathy for his characters, each of then fuck-ups in a variety of ways (sex, drugs, spoiled rich kids, alienated teen, rock-band groupie, Manhattan plutocrats, and, the most sympathetic character, Mercer, a black homosexual from the South teaching prep school in NYC and staying under cover, as too many had to do in the 1970s, which now seems eons ago) I am curious and interested in their state and their fate - and what more can we really expect of a novelist? What seemed at first to be a series of loosely twined NY angst narrative strands really tighten about 100 pages in when, after a long New Year's Eve social gathering in a CP West domain a young girl is short in the Park and two of the characters we've been following are potential suspects (though we know they're both innocent, the cops don't know that). Not to mistake this for a crime novel, even though a crime occurs, it's moved up a big notch in my estimation as I can see that, subtly, slowly, and surely GRH knows ho to build interest and suspense within a narrative of high literary style and aspiration.