I had the chance to pick this up in Barnes and Noble the other day, and I'm glad I skimmed through it before buying it.
First, though, some good news--the book does have a bit of merit. Having a huge list of science-fiction movies and information on each is pretty cool. But Henderson should have stopped there.
Instead, he decided to add his opinions to the mix, which are actually wrong. It's rare to find an opinion that is factually wrong, but he manages to do it--his opinions are consistently in poor taste and inconsistent in logic (as another reviewer has noted). He will praise a movie for one thing and then criticize another for the exact same quality.
He has called some of the worst movies ever (Alien: Resurrection, Armageddon) classics and said that they excel where all other movies fail. He has a huge vendetta against James Cameron, for some reason, and calls all of Cameron's good movies (The Terminator movies, The Abyss, Aliens) overblown and pointless. To praise Alien 4 for being new, innovative, well-acted, with good action scenes, and being fun while criticizing Aliens for being dull, over-focused on special FX, and poorly written... well, that's just wrong.
Everyone can have their opinions, whether they fit with the majority or not. But you need to be consistent in your opinions.
Henderson's other major flaw is that he is completely unaware of the outside world. He never once mentions, "This movie was very popular" or "This movie was not well-received by critics." He simply gives his own opinions and writes them in such a matter-of-fact tone that it doesn't feel like you're reading a book of opinions at all.
I would've been thrilled to read a book that had fresh, bold opinions on movies if they were written well and if the author didn't seem like a complete #$!hole.
In closing this review, I'd like to point out something on the Amazon.com review above. It mentions that the book would be good for "Indie film makers" and the like--people who are supposed to be going against the grain of mainstream Hollywood movies. This strikes me as very amusing; I can't think of a more false statement. Henderson's opinions are almost exactly like a mainstream, Hollywood hack artist. If you want a breath of fresh air, just think for yourself instead--this book is poison for the mind.