I haven't read the book. That's why I'm not attacking the book, but only specific claims which people who read the book repeat. Most notably, confusing people that the "little guy" is David Einhorn, confusing everyone (including Mark Cuban) that HFT's have some ability to "jump in front" of other orders (they don't), and obfuscating the fact that HFT's pulling their orders is just a way of price discriminating against big guys.

spreading FUD and launching ad hominem attacks on authors

The only person spreading FUD is Lewis. I'm unaware of any ad-hominem attacks on him - all I see is "Lewis is wrong in X,Y,Z, did that idiot even talk to an HFT?" (Not an ad hominem Lewis being an idiot is orthogonal to the real argument, which is X,Y,Z.)