Ultimately, Planet Simpson tries to be an entirely different beast, but, fails. It tried to be a cultural analysis of the TV series and its impact on society, particularly American society. However, in the end, it indulges in its author's love for the series too much.
The narrative structure is not coherent enough to sustain interest in the book. Turner too often than not tries to start a dialogue on a particular point of fact. That fact being how, in whatever way, that point backs up his belief that the Simpsons in the most culturally important element of the late 20th century. Unfortunately, he never backs up the statements he starts to make. He many times starts off with a good topic, but, diverts off. Punctuated with his own words saying he's about to state an example of what he means, he veers off his topics entirely. The text is reduced to mere catalogues of episodes, moments, details, and the like. He completely forgets the vast majority of his main points and never returns to them.
Because of this somewhat rambling style, the chapter structure just does not fit it. Each seems way too long and bloated for its own good, because nothing is ever established in each section. Just collections of ideas, peppered, of course, with numerous story descriptions and notes.
This might have worked far better as an episode guide, with Turner taking asides to express his commentary. His love for this show and extent of knowledge on it is firmly established within the book. In an attempt to culturally analyze the series, though, he has failed to make a point more often than he succeeds.