What is the author's style in A Guide to Berlin by Vladimir Nabokov?

In describing "A Guide to Berlin" in 1976, Nabokov wrote that "despite its simple appearance this Guide is one of my trickiest pieces." The simplicity Nabokov referred to is the story's apparently straightforward "guidebook" structure: its five seemingly cut-and-dried sections, each dealing with a different aspect of Berlin life, from sewer pipes and streetcars to working Berliners, the zoo, and a pub. After the opening frame, Nabokov presents five sections that begin with realistic, "guidebook-like" descriptions but that open or expand out into philosophical or impressionistic language.