This is the screenplay of one of the more important movies of 1980s - introducing two important themes connected with minorities: racism and homophobia. Kureishi managed to weave them into a single and gripping plot. Reading the screenplay, however, as screenplays always do, is like licking sweets through a glass-pane. The real thing is the movie, so go ahead and see it.
P.S. If you still feel like reading it, try to get the 1996 edition which includes a number of Kureishi's essays on related themes.