As someone who is often put off by an overabundance of "style," I began doubting my ability to finish this book on p. 2 with the description of a gas station restroom that begins, "If you were tracking left to right in here, things would look like this as you drifted along making sense of it: empty paper towel dispenser with just a tiny torn tag of why-bother hanging from the stoic slit of its chipped metal grin; then the scratched-up, dented, bereft vending machine..." Something about the bloated verbiage of that paper towel dispenser really made me want to stop right there, in the second paragraph.
My advice for anyone with a similar reaction? Get through the first chapter. The style does stay fairly consistent throughout, but it also develops a natural rhythm (and stops being about gas station restrooms). It's kind of the stream-of-consciousness narrative of a man in crisis—or rather crises, most at least partly of his own creation. While Matthew has difficulty forming coherent sentences and behaves much of the time like a full-bodied myoclonic jerk, you gradually come to appreciate that this was once a functional human being (though I wouldn't have minded a little more evidence of that) who's just really overwhelmed by life right now.
And if you accept that this is ultimately a fable of survival rather than a documentary of a futile downward spiral, it may be easier to enjoy the humor, which I think Alan Tudyk should bring to life if they make a movie out of the book.