Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Despondent
We're sorry to break it to you, but this is a sad, sad book. Guys, the New York Times called it "a kind of Death of a Globalized Salesman." And if there's anything sadder than Death of a Salesman, it's Death of a Salesman topped with the bitter cherry of globalization. (Source)
Our main man Alan Clay is at the lowest point of his life—and that's at the beginning of the work. Eggers' tone is subdued and brooding throughout the work, reflecting his protagonist's state of mind:
But he hadn't known at the time that his decisions were short sighted, foolish or expedient. He and his peers did not know they were making decisions that would leave them, leave Alan, as he now was—virtually broke, nearly unemployed, the proprietor of a one-man consulting firm run out of his home office. (I.10.4)
Oof. That tone is as depressing as Alan's situation. Take a look at how the tenor and rhythm of that long, slow, draggy sentence really sounds. It's like Eggers wants us to land hard on each of those words: we get two different lists of Alan's shortcomings ("short sighted, foolish, or expedient," "virtually broke, nearly unemployed, the proprietor of a one-man consulting firm run out of his home office" in the span of two sentences.
Like we said: it's an unhappy book, with an unhappy tone to match.