The Last Olympian (Rick Riordan)
For four previous books, I felt like Percy was very BLAH as a hero. I felt like he didn't really learn anything, and he was more passive about his fate (related to the Prophecy) even if he was part of the action.
Not here.
Here, I finally thought that Percy was worthy of the Prophecy. He finally stepped-up ... he took what was needed, he took charge to organize the half-blood campers to join forces and protect Olympus. He showed his ability to lead. It was a little bit too late for me to completely like him (it took 5 BOOKS?!?) but he was different this time around. I LOVED how everyone fights -- it showed the Gods that their kids were worthy of their bloodline. Oh, and I loved Hestia here, and her words about being the Last Olympian. Really good.
I loved the ending, how the prophecy was fulfilled but at the same time, it wasn't really what we thought it was. I liked the twist with Luke.
In overall, a great wrapped up to the whole series. I think this one and The Titan's Curse are my favorites.