Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Sympathetic
The characters of The Namesake sure do make a lot of mistakes. They keep secrets, make misguided decisions, and screw up just about as much as the rest of us. It's a good thing, then, that our narrator tells their story with a sympathetic tone.
Just take Moushumi's story, for example. Of all the characters, she probably makes the biggest blunder, and the most hurtful. When she cheats on poor Gogol, it would be easy to write her off as a cruel, unloving wife. Yet that's not the Moushumi we have come to know, and that's all thanks to the tone of the novel. Not only do we get closer to her perspective as the narrative shifts focus to her thoughts. We also get her story told in kind, compassionate terms:
And yet the familiarity that had once drawn her to him has begun to keep her at bay. Though she knows it's not his fault, she can't help but associate him, at times, with a sense of resignation, with the very life she has resisted, has struggled so mightily to leave behind. (9.17)
This passage shows us just how much Moushumi is struggling with both her marriage and her own identity. She had clearly once been "drawn" to Gogol, but she is no longer. The narrator is careful to assure us that Moushumi doesn't blame Gogol, which earns her some sympathy, and when you consider the fact that all of this marital strife comes from the fact that Moushumi has "struggled so mightily" it becomes hard to think of her as a villain. She's human, and this novel is humane in tone.