Harry Potter and the Half-Blood Prince

I feel like, in a way, JK Rowling went back to her roots. For me, the previous book, the Order of the Phoenix, was such a slog it took months for me to get through. In its attempt to become darker, it became boring; it lost its charm and character that made the Harry Potter series unique and fun to read. I feel like the Half-Blood Prince managed to keep the darker tone interesting because it was able to better keep that sense of magical, high-school wonder whilst navigating the darker aspects of the plot.