I hesitated between three and four stars largely because this book, which is so measured in both pacing and language, felt somewhat rushed in the end, but I have the feeling some of my qualms are of the "need to think more about this" sort.
This is my first Maugham, and I don't think my last. I loved the economy of his language especially; it's just short of what I'd call spare.
Apologies if the rest of my comments refer to the movie heavily, but I was surprised by the huge differences between the two. I like both on their own terms, but it should be noted that the book is not really a romance the way the film is. Aside from plot (beginning with events in the cholera-stricken city), the other major difference is that we stick with Kitty's perspective in the book, which I liked. It's truly her story, and that accounts for the plot differences as well in the translation to film. In many ways this is a redemption tale, and I love Kitty's complexities. Just when you think she's found her peace, it's clear Maugham recognizes things aren't so easy (and believe me, they weren't easy to begin with). The book is both frank and lovely.
There's some discomfort with the colonialism--the Chinese are servants, found to be repulsive (though Kitty comes to adore the orphan girls), or seen as sources of ancient mysticism--but the character of Waddington upsets that a bit with his Taoism (something Kitty ultimately rejects) and embrace of the culture. There's also Colonel Yu, though he's not present much. And one of my favorite scenes occurs between Kitty and Waddington's (nameless?) Manchu princess when she offers the slippers.