Luv2go, I liked the book and while it's not essential that you read it to enjoy the play at all, there is a benefit to having a familiarity with the source material, which is that you will appreciate the expert work done in adapting the novel for the stage.
How many clunky, lazy, chop and drop adaptations of books, play and movies do we see every year? There's a reason why there's an Oscar for best original screenplay and best adapted screenplay. It's an art to adapt well, and it seems more and more that no one knows how to do it.
It just makes it extra wonderful when you think, "They can't turn 80 pages of War and Peace into a musical" or "A graphic novel about a lesbian whose father kills himself- won't work," or "A group of near-obscure writers in a dilapidated Brooklyn home taken from an episodic non-fiction book won't fly," and then the creators are able to create something so special and surprising. You can obviously still appreciate these pieces without knowing the source material, but it makes it them all the more special when you do.
Marie: Don't be in such a hurry about that pretty little chippy in Frisco.
Tony: Eh, she's a no chip!