Memoirs Found in a Bathtub unavoidably evokes Kafka and yet it would be an injustice to call it derivative.  Lem is capable of an amazing knack for characterization.  He is wildly comic, he is sardonic, perplexing, insightful.  His narrator inhabits a sort of backup Pentagon called the Building, buried in a mountain, cut off from the outside world, or perhaps from reality.  The whole novel deals with his striving to discover what his mission is and the name of his superior.  The total preoccupation of the Building and everyone in it is a subversion and espionage, of which Lem makes Jovian mockery.

Theodore Sturgeon, The New York Times Review of Books