Humbert's prose is strewn with alliterative phrases, and I found most of them delightful. I like alliteration; I realized that first when I read Sir Gawaine and the Green Knight, and later when I read the poetry of Oscar Wilde and Charles Algernon Swinburne.
But alliteration as a literary device has been dead for quite some time now, especially in prose. Nabokov seems determined to not only sneak a few alliterations here and there, but to flaunt this device throughout the book. I wonder, again, at the background for that stylistic decision, and how it was received when the book was published. Also, has Nabokov used alliteration in any of his other works?
P.S. avva gave me a fascinating explanation of Nabokov's treatment of the Russian concept Пошлость (poshlost'), right here. Go read it.