I read a review of this book in a magazine, and I was intrigued by the concept: Michael Hart's "The 100: A Ranking of the Most Influential Persons in History" deals with actual people; wouldn't it be possible and useful to do the same with fictional characters? Yes, it would, but, unfortunately, the authors don't execute the concept very well.
The problem for me isn't the rankings. After, all, they're admittedly subjective, and in the end, they don't matter that much any way. The thing that I found jarring at first-- and then grating as I read on-- was the uneven quality of the essays. I suspect that this was in part due to the simple fact that there are three co-authors. It would be very difficult to coordinate the styles and lengths of the essays.
More seriously, though, they clearly didn't attempt to coordinate the point of the essays. That is, some of them are straight biographies. Some are pop-cultural analyses of the significance of the characters. Some are political screeds. Some are failed attempts to be cutsie, best illustrated by the essay supposedly written by an author's dog. Many of the essays read as though they were responses to homework assignments that were written at the last second by a student hoping that his teacher will mistake generalities and clever wordplay for content.
Now, this isn't to say that I hated the book; in fact, I actually liked it. It's just that it disappointed me. With a little more authorial discipline-- or maybe stronger editorial control-- it could have been a GREAT book.
So, in summary, I think it's worth reading, and it's entertaining, but I believe it could have been so much better.