There's no doubt in my mind that RR is the US Rowling. Similar premise - gifted kid goes to special school in order to fulfil his destiny and save the world, only this is Greek gods not wizards. Percy is now 16, and about to find out whether he really will defeat Kronos, the Titan enemy of Olympus. Though really he'd just like to have his first real kiss with either Rachel or Annabeth (daughter of Athene).
Wouldn't you know it, all hell is about to break loose to stop the hormonal rush, and Riordan sweeps you off from the first page, when a pegasus lands on Percy's stepdad's car bonnet. It is huge, huge fun, and the jokes are almost as good as the battle scenes. Percy has grown emotionally from a scared boy with dyslexia and ADHD to a brave young man who even wins grudging admiration from the Lord of Death. It's his relationship with other young demi-gods, and his humility, which save the day.
So why not give it five stars? Technically, it's far slicker and smoother than Rowling. The author has done his homework about Greek myth, and is gloriously funny about transposing this onto modern America. Yet Rowling's uneven series has a real feeling of magic about it, and a depth, that is rare. It goes deeper, and is more fully-thought-out in every eccentric detail; it doesn't go for easy laughs all the time; it deals with kinds of pain that are more mature and difficult than having a vile stepfather or a dysfunctional family. All the same, I can't wait for the film.