Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Unsentimental
As a Realist writer, Henry James is committed to being objective and unsentimental about the characters and situations he writes about. That doesn't mean that we can't feel sympathy for the characters. It just means that we can't expect the narrator to. Even when the book's action heats up, the narrator retains the same removed tone and continues to describe people's thought processes in deep detail. Just check out this early passage from Kate's perspective on her father:
No relation with him could be so short or so superficial as not to be somehow to your hurt; and this, in the strangest way in the world, not because he desired it to be—feeling often, as he surely must, the profit for him of its not being—but because there was never a mistake for you that he could leave unmade or a conviction of his impossibility in you that he could approach you without strengthening. (1.1.1.3)
You still with us? Reading that sentence was kind of like choking down a sleeve of saltines without a glass of water. It gets an A+ for dry and super unsentimental. It reads like a really eloquent medical journal article on scumbagitis: the disease that Lionel Croy clearly suffers from. There's no hand-wringing or moaning about how sad it is that Lionel is a d-bag.