Yes, the play really does retell most of Pulp Fiction using Shakespeare's language and times, swapping opium for heroin, ambrosia for Mia's milkshake, a stallion for Butch's motorcycle. The dance scene and monologue about a pocketwatch remain unchanged, amazingly. It all works, partly because Pulp Fiction is a really good movie, and partly because Her Majesty's Secret Players, the theater group that originated the production in LA, doesn't take itself too seriously. With the exception of a flaccid interpretation of Marsellus' "medieval" line, the dialogue moves as briskly and as floridly as Shakespeare's real verse. It's engaging, clever, and very, very funny.
There are still several shows to be had. Go see it!