Flash Boys is Michael Lewis's version of Patterson's Dark Pools. It is equally terrifying, but in Lewis's typical populist flair. Lewis is such a successful author partly because he can take a topic like this and really humanize it, he crafts a narrative around the idea, and he drives home the one narrow slice of the story that he wants to tell. That isn't to say that any of it is wrong, I just dislike being force-fed. Something I think Patterson captured well in his own book, and which Lewis fails at, is how high frequency trading is being driven by the system itself. It is a consequence of technological progression, not an evil scheme. That isn't to say it's good, or healthy... obviously it causes volatility, and it opens the door to nefarious practices (which Lewis is happy to highlight extensively). But the point is that the intention isn't evil. Banks can't NOT take part in HFT. To me, that's the truly interesting story - not the Mr-Nice-Guy RBS Banker who wants to save the world because it's by-golly just the right thing to do.
I like this book. It's easy and fun and interesting and more than anything it's popular, so its getting a pretty wide bucket of people thinking about investing and computers and how the system works and where it's all heading, all for the first time - I like that a lot. But as far as getting an objective and slightly more holistic (or at least, less biased) view of HFT, I very much prefer Dark Pools.
Totally off topic, but there was one passage I really liked about why Russians were such good computer programmers. The argument was that in the '50's and '60's Russia was a mess, and any time spent actually using a computer was heavily rationed. So programmers had to learn to write their entire programs by hand, on paper. Then when they actually got to use the computer, they just typed it all up and ran the code. I can't imagine the kind of mental focus, foresight, and discipline it would take to be able to write any moderately complex code out by hand. But wow - take someone like that and give them a laptop, and just imagine what they could do. (Spoiler: I guess they could write out algorithms that trade securities each microsecond according to millions of individual and mutually dependent parameters.)