I'm an unapologetic lover of children's literature -- really liked the Harry Potter books, grew up with The Hobbit, The Chronicles of Narnia, and some (now) obviously horrible books by Piers Anthony.
So when I heard that my 11 year old nephew really loved these books, more than the Harry Potter books, I gave them a try. I read all 5 books, in order, but didn't really like them very much. They're sort of like a cross between Harry Potter and Greek mythology, but with all the action, including Mt. Olympus, centered around present day Manhattan.
What could go wrong, really?
Yeah, everything you just imagined as an answer to that last question is pretty much true. This really isn't a very good series of books. I totally understand why my nephew liked them -- they're basically fun books with a teenager in control, with some tortured Greek mythology thrown in the mix.
Anyway, since I read all 5 books, they're obviously not horrible, but they weren't really what I was hoping for. The mythology is pretty dubious, but it did cause me to run down the rabbit hole on Wikipedia a few times to learn about various Titans and minor gods, so that's not all bad.