I should probably preface this by saying that I haven't seen the movie yet, so the book kind of exists in an insular book-bubble for me, although I totally pictured Kate Winslet and Leonardo Di Caprio as the main characters. I'll probably end up seeing the movie, but now I am fully braced for how depressing it will be and know to only watch it when I'm in a good mood so that I don't end up hanging myself.
In other words: It's one of the more depressing books I've read lately.
On the upside: It's beautifully written. The characters, while not necessarily likable in the absolute sense of the word, are relatable. It's an interesting study of gender roles and societal restrictions in the 1950's, not just in the marriage between the main characters but from top to bottom.
But, again, it's highly depressing. It left me feeling all sad and gutted and empty. You probably should only read this book if you're single (if you're bitter about relationships/marriage, you might actually gain happiness from this book, but you are also probably a serial killer or something) or if you have special powers that keep really depressing books from getting all up in your head. Or if you just really like books about the various ways in which the 1950's kind of sucked for people. If you fulfill any of these categories, though, look into it, because it is a well-paced and well-written book.