At the end of the French edition I have there is a short comment of the author about the history of The Joke, including its interdiction in Czechoslovakia and the bad translations it had to go through afterwards. And finally, Kundera seems to feel relieved that now, when everyone forgot about the invasion of his home country, his readers don't see The Joke as a political novel, but simply as a novel.
Indeed, some of the reviewers on this site needed to mention that "one does not have to have a particular political interest to enjoy this book", "The Joke is, frankly, not very political" and I simply wonder why such a fear of the political. No doubt, Kundera is way beyond a simple journalist describing life behind the Iron curtain. But why would a romance or science fiction novel or even a "just novel" be better than a political one?
Take the political out of The Joke and we're left with an absurd novel. An unexplainable and ridiculous trouble over a post card, the hard life of a worker in the coal mines, where he has to stay for unclear reasons, a "stupid" young lady who doesn't seem to understand a man's idea of love and an equally stupid hateful sex affair which pushes another na?ve woman to suicide. Young, modern Miss Brozova, to whom Zemanek's and Ludvik's past were equally blameable, aberrant and indifferent, was thinking the same way.
I have asked someone about the movie made after The Unbearable lightness of being and all I heard was some vague memory of a few hot sex scenes. I have the feeling that both books are reduced to that in the view of many readers and it's a pity. If this is what we are looking for, I would recommend Pascal Bruckner - Bitter Moon: it's brilliant and no trace of politics mixed with sex.
The Joke is a masterpiece which combines them. And the postcard is only a minor but well chosen example of the many possible "jokes" of a regime. Kostka, the religious, didn't have to be caught with any postcards to get in trouble and his life is not any less a bitter joke. He tried, humble, the impossible reconciliation of his belief in God with the communist fatalities and still lost. Jaroslav, the folklore lover, tried a similar adaptation and ended up in an ambulance. Their lives, the romance, the sex, are all influenced by political circumstances, more or less directly. Which is why it's simplistic to judge them or Ludvik for his hate, need for revenge and incapability to forget, or the whole situation as a result of a badly misunderstood joke on a postcard. Isn't it why we love Kundera? Because he explains it so well and encourages us not to be simplistic?
Some said they found in the book many problems any of us can have at some point in life. Since the "some" come mainly from a democratic USA, I have serious doubts. And serious hopes that no one will ever have such problems. Unless, of course, we are talking about girls refusing to sleep with guys, the masks and stupidities of young age, rape, hate, revenge - all of them thought taken out of context, and which may indeed (and unfortunately) happen anywhere and to anyone. Actually, let's get rid of this low infatuation with ourselves which tells us to like a book only because "we find ourselves in it"; we do that enough in relationships all the time.
I really don't mean to give definitions and put The Joke in a literary category/genre etc, I even understand why Kundera had enough of his novel being considered political. I just don't think the other extreme is better; it would mean not only deleting pages and pages of the book, but also neglecting a big idea which makes the novel a believable, explainable and logical whole.
In conclusion, it's a rather simple (as in classic, not simplistic) novel (comparing to say, Immortality), yes it is not ONLY political, but lets not cheapen it by recommending it to Harry Potter fans.