This should be two stars, really, but I already feel blasphemous enough having such a low opinion of a Rick Riordan book, no need to get even hastier than that. Lol, but it's also rated three stars because despite my reservations, which I will attempt to detail below, I still read all 565 pages of this book in one sitting (well, almost). 
 It is perhaps unfair to this book, but since it is a spinoff (or in some sense a loose continuation) of the Percy Jackson series, there's no help for it: this book will be seen in light of the previous series. And let me tell you, it falls far, far, far, short of that light. Very, very far. 
 When The Lost Hero starts, we are introduced to the people who make three of the seven heroes the newest 'doomsday prophecy' talked about. Eh. There's the amnesiac Jason, who later turns out to be the son of Zeus, Piper, who's a daughter of Aphrodite, and Leo, a child of Hephaestus. At the same time we find that Jason is an amnesiac and is been raised somewhere not Camp Half-Blood, we find that Percy Jackson is missing. 
 My main problem with the book is that the characters were lacklustre, and so making the story itself lacklustre. The Percy Jackson series started off with Percy and his friends as tweens, and we watched them grow through the series. Jason, Piper and Leo are well past their tweens - I believe they were in their mid-teens, gauging from a few discussion, but they behaved like were 9-going-on-10, especially Leo. That was a huge turnoff for me. I agreed with the review that stated that Piper was more a Mary Sue than anything else. Jason's story, unlike Percy's is the story of a hero who's already come into his own; he just needs to remember it. I am sorry to say I didn't believe it one bit. 
 Additionally, Percy and his friends didn't just grow through the series, the grew in each individual book. In Book 1, Percy went from underdog boy who has no idea what's going on, to a levelheaded boy who while not quite a leader, had the capability of becoming one someday, until his leadership is cemented somewhere around book 3. In book 1 Annabeth goes from sullen comrade to partner-in-adventure, and then friend. Leo, Piper and Hazel, exhibit no such growth. Leo is still immature, and Piper is even more Mary Sue-ish by the end. Jason is same old, same old also. 
 The quest, aka what is supposed to be the meat of the story, felt more like child's play than something that should be taken utterly seriously. The monsters and the gods alike (with the exception of Hephaestus) talked like....like they had no sense. None of the sense of urgency Percy's quests had. 
 To be sure, part of the joy of the Percy Jackson series was the novelty. But it wasn't just that. It was well-drawn characters, inspired writing, a fascinating journey, a sense of belonging with our intrepid demigods. You get none of that here. Flat characters, uninspired writing and a decidedly boring adventure, and no sense of affinity with said flat characters. 
 So you can see that even though I read this book in almost one sitting, there was no joy in it. I have already bought book 2, The Son of Neptune, because I love, love, love that title and the cover, and I peeked ahead to find out Percy returns. 
 Let us hope that with Percy, Mr. Riordan can recreate the old magic...heck, even make new magic. I will be so devastated if Mr. Riordan manages to makes Percy as flat and boring as he did Leo, Piper and Jason. Wish me luck!