Being serious when no one else is means you are not serious at all. Life is essentially a game, and the point is to have fun while playing.
Kundera's style is truly unique, as it charmingly captures many truths about relationships and the pursuit of love (or sex). He has a talent for exposing subtle philosophical fragments and metaphors throughout his novels, which makes for a great read.
However, there is one drawback: the somewhat obsessive tendency to center each story around women and sexual attraction. This focus sometimes causes him to miss opportunities for other deeper reflections.