Nabokov at his most creative and ingenious. The book could be read as parody of literary criticism at its worst, and is often screamingly funny. Some critics are a bit like Kinbote and try to make the work fit their thesis, much like the legendary host, Procrustes, who lopped off the arms or legs of his guests to fit his bed.
Kinbote's insane asides and manic determination are the core of the book - Shade's poem is ho-hum and probably deliberately so. Even the index is funny! And indexes are funny - and often an accurate glimpse into the author's ego.