I didn't like this one. I should qualify that: I didn't like this one except for the last thirty pages. It's a novel about love and sex. I could only identify with one character and the dog because everyone else was busy sleeping with people who weren't their spouses. There are only a few types of novels I don't like: mysteries, novels about people being taken away or imprisoned (I find those incredibly frustrating, and it's why, as much as I love The Bean Trees by Barbara Kingsolver, I couldn't get through its sequel, Pigs in Heaven), and novels in which the principal plotline focuses on infidelity.
There are five important characters: Tomas, Tereza, Sabina, Franz, and the dog, Karenin. Tomas is married to Tereza, who adores him and is generally faithful, and he likes to have affairs with many women. He has a prolonged affair with Sabina, who, after Tomas dies (I think - the story isn't exactly linear) has a prolonged affair with Franz, who is also married to someone else. And then there's Tereza's dog, who is very nice and doesn't have sex with anyone, though, in Tereza's dream, gives birth to two rolls and a bee. Kundera explores the difference between love and sex and how love affects people differently. I wasn't enthused until the last thirty pages when the dog dies. That made me cry.
I probably should have liked it more. The only other Kundera novel I've read is Life is Elsewhere, which I adored, though I don't really even remember what it's about. I read it five years ago, or so, so I guess that's to be expected. The Unbearable Lightness of Being reminds me of the only Paulo Coelho novel I've read, Veronika Decides to Die, which annoyed me in its preachiness. A first-person narrator (Kundera himself?) tells the story from the first person: the novel is generally written in third person, but the narrator breaks in often with nonjudgmental ideas about what's going on. It was like inspirational nonfiction (which annoys the hell out of me) on top of what could have been a good novel - like Kundera was filling in all the spaces the reader should be able to figure out on his own.