I finished the Half-Blood Prince yesterday, and it is was incredible! The mysteries, humor, darkness, Voldemort getting stronger and stronger, Snape, Dumbledore dead, etc. Plus, I really liked the fact that J.K Rowling added more teenage reality. For instance, Ron dating Lavender and having a fight with Hermione, or Harry starting to develop feelings for Ginny..... Everything was so well written!!
IT WAS AN ABSOLUTE MASTERPIECE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!