Instruct: Classify a review into positive or negative sentiment.
Query: Very thoughtful book, but complex

While its not the type of book that you could describe as exciting, the conclusions by Romm are well supported by his analysis of all the facets of hydrogen as a an energy medium. The chief conclusion being that hydrogen has a host of pitfalls, ranging from the fact that its really an energy transfer medium, expensive to make, to the major distribution and storage problems.It confirmed to me that beliefs of us being rescued from our impending energy dilemma by hydrogen vehicles are really off base.It is a much more professional and credible piece of work than Jeremy Rifkin's "The Hydrogen Economy" which so conveniently glossed over the same stumbling blocks for hydrogen's future that Romm dwells on.