Jim McTague - Washington Editor of Barrons - slams high frequency trading in his forthcoming book, Crapshoot Investing: How Tech-Savvy Traders and Clueless Regulators Turned the Stock Market into a Casino.
McTague notes (via professor Robert D. Auerbach) that high frequency trading puts human traders at a huge disadvantage, who can get creamed by the high-speed algorithms:
It has become a shark tank and we are the anchovies.
For background on high frequency trading, look here.