I'm in awe of Dan Simmons. He writes really long books of the sort I'd never dare attempt, he writes complex series and standalones, and he writes in several genres. When he wants to, he writes lean thrillers like Hard as Nails. In other words, he can do just about anything.
Darwin's Blade is a thriller, but it's not lean. It's long, and it's filled with all kinds of research and ancedotes relevant to accident investigation. If you're interested in accidents, particularly auto accidents, this is your kind of book. Darwin Minor is the protagonist, and he's an ace investigator. It turns out that he has a past (no surprise there), and the book morphs into a sort of Bob Lee Swagger novel. If Simmons and Stephen Hunter sat down to talk, they could go on about guns and ammo for, at a rough guess, thirty-seven years without repeating themselves. There are a couple of set-pieces in the novel that Hunter would surely admire.
The plot has to do with the Russian mob taking over the fake car accident scams in California, and it didn't really make a lot of sense to me. Apparently the Russians just kill people for the hell of it. Or something. Anyway, they have to be stopped, and Minor, along with the FBI and a bunch of task forces, is up to the job. Some might find the book outrageously padded (we even get mathematical formulae), but it's entertaining all the way. The ending is clearly a set-up for a sequel, but as far as I know, there hasn't been one.