I think most of what [Boyd] has presented as Nabokov's "deep" side is indeed shopworn, and was shopworn long before Nabokov came on the scene. As Boyd has described it in the pages I've read by him, the "philosophy" is a hodgepodge of familiar ideas--a bit of Ancient Wisdom here (Gnosticism, neo-Platonism, etc.), a spot of pseudo-science there (Blavatsky, Steiner, Dunne, Ouspensky, et al.), pretty standard intimations of immortality and nature mysticism, and some ideas about design that have been around for a very long while. 

This isn't to say that I don't think there's depth in Nabokov.  Pale Fire is a deep novel indeed, a novel that I greatly admire, but I don't think Boyd has the handle on what the depth consists of. 

Much of Nabokov’s work is best understood in terms of the possible survival of the individual consciousness (personality and memory) after death. Death is, speculatively, merely the dividing line between levels of consciousness. These levels (or worlds), one exercising a degree of influence over the events in the other, form the basic conceptual categories underlying most, if not all of Nabokov’s work. Much of the technical virtuosity in Nabokov’s work is in aid of hinting at this relationship between dimensions. This approach, sometimes known as the ‘metaphysical’ (as opposed to the earlier ‘metaliterary’) . . . dominated the 1990s. It is the matrix for most current criticism and is, in my view, basically sound, a productive paradigm for continued research. . . . My present discomfort stems from the thought that this dominant critical paradigm discourages critics and readers from attending to the very concrete details that constitute the basis of Nabokov’s stature as an artist. They also tend to ignore the wit and humour that are so central to his work. For the sake of argument, let us suppose that Nabokov is in fact a ‘dirty’ writer who sometimes appeals to the reader’s prurience; let us assume that his values are sometimes less than humanistic, and that his other worlds philosophy is, in itself, badly shopworn. Would acknowledging such assumptions significantly diminish our delight? Would Nabokov be less the consummate artist? Apart from whatever heuristic value they may have, our reigning paradigms should be regarded with scepticism, lest they deflect attention from the area of Nabokov’s greatest originality--the brilliance of his style and wit. --Johnson and Boyd, “Prologue: The Otherworld,” in Nabokov’s World, Vol. 1: The Shape of Nabokov’s World (Palgrave-Macmillan, 2002), p. 23.