I must have read the preceeding write-ups many a time, and must have assumed that I had nothing more to add on the subject of infinite jest. But, reading the above descriptions, and for that matter, most other descriptions and discussions of the book elsewhere, I notice that one thing is not commonly mentioned: the plot.
Much like some other famously complex 20th century novels, such as Finnegan's Wake and Gravity's Rainbow, plot is not the first thing that is usually discussed about infinite jest. The first things mentioned are usually the endnotes, David Foster Wallace's vocabulary, and perhaps a comment about what a smart ass David Foster Wallace is. If the content of the book is mentioned, it usually centers around one character, often peripheral, or else it features on an artifact or incident in the book, which is also often quite peripheral. Sometimes, the serious themes of the book, such as addiction, are discussed. All of which is very well and good, but we are still reading a novel, no matter how different of one.
And this novel has a plot. The plot begins in media res, or perhaps post media res, if such a thing exists. One of the two protagonists of the story, Hal Incandenza is attending a college interview. Because he was an athletic protege in an institution ran by his mother, the college is curious if his academic record has not been somehow biased. They don't want to acquire a tennis star who is hiding his illiteracy behind a doctored academic record. So Hal stands up and makes an articulate, heartfelt statement that shows his academic ability and interest. That is what we hear: what the people in the room hear is Hal going into an animalistic seizure of some sort. After the chapter ends, the book begins in the past. The entire plot of the book is based around how the seemingly intelligent, if troubled Hal, turns into what is seemingly (at least to others) a monster. The many disparate elements of the book, which seem to include enigmas, mystery and probably many Red Herrings, are not just the curiosities and in-jokes that many have accused Wallace of heaping on the reader. They all, in some way or another, point to the basic plot of the book, of how, why (and perhaps whether) Hal Incandenza lost his sanity. This is not to say that any, or even most people, would say that the plot is especially well-handled. The plot is never resolved cleanly, and it is possible that the book is a gigantic shaggy dog story. However, for the most part, no matter what stylistic elements or weird objects David Foster Wallace is throwing into his story, it is somewhat safe to assume that they are actually meant to be relevant to the book's central plot.