I have mixed feelings about this. The beautiful writing is a distraction from the story itself which seems intriguing and quite fascinating when it starts but winds down somewhere in the middle. 
 Zafon treats this novel as a piece of exquisite art with lovely words that will long be memorable and the mystery he builds has an enchanting ring to it. However it gets exhausting to read when a simple conversation takes forever to finish. That could also be the reason why all characters sound almost the same. They have same convoluted way of arriving at a point as is Daniel (or even Clara for that matter) and after a while these characters all seem to be cut from same cloth. 
 Unraveling the mystery was the biggest let down in this book. It gets easier to overlook the characters if the mystery is engaging and unravels in layers. Zafon takes an easy route by making a character write a letter explaining everything. By the end of the book it feels like cheating to have the information dumped in such a fashion. This happens several times in the book where the characters seem to have been introduced to tell their stories which doesn't really resolve much but adds to the building mystery. 
 The book was a good read and it was enjoyable in most of the places. Had it dealt with mystery and intrigue with attention to details and characters, it would have been amazing.