I Hated, Hated, Hated This Movie is a great title, but it doesn't really sum up this book. It's a collection of reviews of movies rated between zero and two stars - and if you know Roger Ebert's ratings system, you'll know that two stars isn't by any means a total pan. And that's where the book gets weak.
The zero to one star reviews are truly funny; it's quite amusing to read the distillation of bitterness and hatred that comes from forcing a movie lover to sit through a terrible movie. On another level, it's also quite amusing to try to imagine how these movies ever got made in the first place - some of them leave you wondering how it is that the producers did not notice they didn't have a script until after shooting started. Others leave you wondering why the actors and director didn't take the easy way out and simply kill themselves rather than complete the movie.
Unfortunately, the book is padded with reviews of some movies that it appears Ebert only disliked. And mild dislike doesn't give rise to the same kind of humor as loathing does. Had these reviews been cut, the book would probably have been 50 pages shorter, and it would have been a riot from beginning to end, albeit one that left you with a serious disinclination to go to the movies. (Or, depending on the kind of person you are, with a strong *inclination* to head for the video rental store.)
If the editor, author, or publisher truly felt the need to extend the book beyond the despised movies, it would have been much more gripping and entertaining to include a few four-star reviews - maybe one per chapter? - to show what the other end of the spectrum looked like. That would also have staved off the erroneous impression this book can leave - that either Ebert hates everything or every movie is terrible.
My advice: read it, but not too quickly. There's a limit to how much badness the human constitution can stand. Remember, Ebert didn't see all these movies at one sitting, either.