Harry Potter and the Chamber of Secrets

I was pleasantly surprised by this book. After reading Harry Potter and the Philosopher's Stone I was expecting more of the same middle grade level writing, but, even in the space of one book, JKR's style has noticeably matured, no doubt a necessity to deal with the darker themes presented here. Aside from her constant overuse of ellipses, I found her writing much more nuanced, her foreshadowing deftly dealt with rather than ham-fisted as in the first book, and many of her turns of phrase were positively charming - Hagrid trying to raise werewolf cubs under his bed, Moaning Myrtle blushing silver, and particularly this:

October arrived, spreading a damp chill over the grounds and into the castle. Madam Pomfrey, the matron, was kept busy by a sudden spate of colds among the staff and students. Her Pepperup Potion worked instantly, though it left the drinker smoking at the ears for several hours afterwards. Ginny Weasley, who had been looking peaky, was bullied into taking some by Percy. The steam pouring from under her vivid hair gave the impression that her whole head was on fire.