I think that the idea of appearance and reality is something that underscores the entire novel.  There seems to be a different side to nearly everything presented.  Changez comes to America believing himself the star of his own Bollywood film.  Over time, he sees something else happening.  His work at Underwood Samson is revealed to actually be more predatory than anything else.  Changez's own construction of self is one that is more introspective than originally thought.  Appearance and reality are shown to be different constructions.

Hamid brings the notion of appearances and reality out in his characters to help broaden the idea to its application to the modern setting.  The idea of appearance and reality is explored in light of the  war on terrorism and its view of fundamentalism.  Essentially, the work seeks to initiate the examination of self and world that some of the characters lack.  For example, in seeing Changez as a fundamentalist at the end of the novel, it is evident that his appearance as a fundamentalist might not be indicative of an entire narrative.  There is something underneath the surface of what appears to be.  Here lies his "reluctance."  At the same time, the ending between the American and Changez is one in which there is ambiguity. The potential for the dynamic of appearance and reality helps to prompt a clear discussion between what appears on the surface and what exists in actuality.  What the American appears to be and what he might actually be could be two different realities.  This is similar to Changez, the war on terror, and the view of fundamentalism.  In this, Hamid wishes to suggest that appearance and reality might be two different constructions.  The individual must engage in this process of questioning and analysis in order to better understand how and why this is so.