I would tend to agree with many of the comments made by the (admittedly few) critics; the text was littered with overly complex metaphors and non-sequiturs, not to mention the abundant use of brackets all over the place. It's partly style, I get that, and partly it works (there are some excellent turns of phrase used in places), but overall it is frustrating for the reader; when an entire sentence lasts for several lines with absolutely no punctuation, that isn't style, that's just bad editing.
However, unlike The Guy Who Gave This One Star I did actually thoroughly enjoy the book. It is at once funny, chilling, warm and confusing (confusing in the manner the author intended, aside from the occasionally dodgy prose). This book is certainly worthy of more than one star; whilst correct in their criticisms, its detractors such as those above are incorrect to knock the book completely down on the text - that would be completely missing the point. Perhaps this was the point, to smoke out the boorish punctuation/prose Nazis, but then you start to get into the realm of pseudo-intelectual excuses in irony and we come back to square one.
If anything the book serves to illustrate the kind of man Nabokov must surely have been: stubborn, arrogant and pretentious, qualities which appear in in his main character. It speaks volumes to me that within the preface, written by Nabakov himself, George Orwell is described as a 'mediocre' and 'overrated' author. Nabakov himself misses the point of Orwell's writings - Orwell praised simplicity and the ability to able to present his ideas and stories to as many people as possible. Nabokov, it seems, was more interested in writing his art for art's sake, a book to be praised by intellectuals and other authors. It is a testament to the man that despite this there is an excellent story within.