I recently started reading this book but have not yet finished it. I suppose all books have some value, but if you are looking for insight into some miraculous trading system it ain't here. It does however make some interesting references to market psychology.
I read it in an hour and a half while at Banes and Noble. Fun to read and in some cases insightful, but one gets the feeling while reading it that he does not know how to trade.
For what it's worth, his previous book about mathematical 'innumeracy' is I think worth a look - lots of examples of widespread mistakes made in assessing probability etc.