Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Soap Opera, Sacrifice, and Slapstick
Although this is a dark and serious book, it has that soap opera tone, with lots of gossip, second and third-hand information, and improbable explanations for weird behavior (like Raskolnikov's explanation for why Luzhin tries to frame Sonia). It has lots of minor characters and subplots, many of which simply disappear from the story without explanation.
Still, there is a pervasive mood of sacrifice. Everybody wants to either sacrifice themselves (or others) for what they think is right, or to get what they want. There is also lots of punchy humor, and physical comedy, even in dark moments – like when Raskolnikov slips around in Alyona's blood, or when Pulcheria pulls Marmeladov around by his hair while he screams that he loves it. These three elements work together to creep us out while hopefully keeping us from getting too depressed.