I read this in the Czech Republic once, to see it in its bare setting and atmosphere, although Kundera has really lived in Paris for quite some time. I've read many of Kundera's books and loved them, but many parts of the Czech Republic are positively stultifying, as Kafka conveyed and Kundera says more or less outright in this book. He is describing the atmosphere under Soviet-controlled communism of the past, but I won't take it back.
Funnily enough, The Joke, Kundera's first novel I think, has the sense of hapless machination which victimizes Kafka's more famous characters. But Kundera is always licentious and makes romancing the dullest ciphers feel like epic conquest, which gives his works a constant intricate bloodrush. Kafka's version of this -- written in Czech across a newer shopping centre in Prague today -- is that there is one chain attaching us to earth in the middle, and a second one to heaven.
But truly, Kundera never takes shortcuts and this fable of the complex consequences of any petty act of one's life never settles for cheap romance or vengeance. If I had not read it in the Czech Republic, where existence seems so often grey, or at least, unobtrusive, I would say the main character's complacence to fate was unacceptably sad and deep.