Pale Fire might be, at its heart, a colossal bait-and-switch, but that doesn't make it any less awesome: The heart of the book is a 999-pp. poem supposedly written by one John Shade, poet and professor at Wordsmith College in a town called New Wye. The commentary, which takes up the bulk of the book, is by his friend and colleague Charles Kinbote, who, instead of providing any meaningful commentary on the poem (which is a solid but unspectacular autobiographical treatise focusing on death and loss), finds any slight excuse to go off on tangents about the story of exiled Zemblan king Charles Xavier, a story which he claims provided the inspiration for the poem. King Charles Xavier, we come to understand quite quicky, is actually Kinbote, and the recent death of John Shade has occurred at the hands of the king's would-be assassin.
Schools of thought have cropped up about the novel; Shadeans believe that Kinbote is a creation of Shade, and Kinboteans vice versa. Some believe that the whole thing is made up by a minor character in the book, a Professor Botkin (whose name anagrams nearly to Kinbote), a theory that Nabokov himself has supported. But of course, this is the bait and the switch: Shade and Kinbote aren't creations of each other; they're fictitious--they are creations of Nabokov. The whole argument is the perpetuation of Nabokov's joke, because at no meaningful level can one claim that either character is more "real" than the other.
Pale Fire has been called Nabokov's masterpiece. While it certainly provided some excellent mental calisthenics, it's hard to speak of it in the same breath as Lolita when it lacks so much of that book's haunting beauty. There's a lot of depth in Shade's work and in his depiction as a character in the commentary, but--true to the book's central questions concerning surface realities--it is difficult to extricate Shade's wisdom from the kind of academic pretension that pervades his relationship with Kinbote. Pale Fire may be one of a kind, but Lolita is the better book.