Personally, I think this series is the best series I've ever seen and in all of humanity. My Favorite is The Sea Of Monsters. My second favorite character (other than Percy) is Annabeth.
Ever since I have read these books, I have been intrested in Greek Mythology. Such propelling stories, with mythical prophecies and twists. WOW!!!
I like The Sea Of Monsters because of Tyson. IT surprised me, (cause seriously, A CYCLOPS?!!). It had more action too. I've just started The Titan's Curse, (which I am sure will be a good book.)
The Lightning Thief was a very good book. I had never known what satyrs were until then. (Which I still don't know how to pronounce!)
Overall, these stories are filled with fun experciances that will Spark Your Imagination Read Them NOW!!!