_Flash Boys_ is a terrible book. It's incoherent, very poorly ties the narrative about this case to HFT, gets a lot of trading details wrong, and makes an underdog story out of an attempt by a bunch of bigbank insiders to route bigbank brokerage trade through their new firm. If you're interested in the technical story behind HFT, a much better thing to read is that series of articles that's been running on HN for the last few months.
I'm a Michael Lewis fan --- I even liked _Next: The Future Just Happened_ --- but this book was so disappointing I've actually become disillusioned. What else was he wrong about that I wasn't clued in enough to notice? Do Greek people in reality try hard to pay their taxes? Was Chad Bradford a terrible deal for the A's? Was Marillion a terrible band?