As a student of history with a love (and a minor!) in classics, and little kid at heart I loved this series of books, culminating in The Last Olympian--maybe the best in the series. The obvious comparison is to Harry Potter, but these books are really something different. They're a little lighter, and a little more fanciful, and just more 'colorful.' They are shorter and and just more fun with less dark overtones (imo.)

This last story brings about a conclusion to the whole saga, with one battle after another, answers all your question and even gives our heroes the accolades they richly deserve. It seems its the last one in the series and thats a little sad.