This is by far the best of the four Rabbit books in my opinion, but, as others have said, you should read the others first for maximum enjoyment, and they are all very well worth reading. Updike sometimes places a bit too much emphasis on sex in his novels, for my taste, and Harry's epsidode with his daughter-in-law is not entirely convincing to this reader, but I still think this novel Rabbit at Rest is unsurpassed in 20th Century American fiction, even against such lively contenders as Philip Roth's An American Pastoral, Richard Ford's Independence Day or Richard Yates's Revolutionary Road.
To mention but one episode, Harry's lone drive to Florida, reflecting his flight in the earlier Rabbit Run, is an extraordinary tour-de-force with the car radio bombarding Harry's brain cells with news items current at the time (baseball results, evangelist Jim Bakker's trial, an ailing new-born panda, the Lockerbie bombing aftermath) and with "golden-oldie" radio programmes, evoking exquisitely painful/pleasurable memories of long-ago girlfriends, including his wife Janice, the "little mutt" who worked at the nut counter in Krolls long since defunct Department Store, whom he is currently running away from (yet again.)
A wonderful book and definitely in my top ten.