I didn't see the movies, but I saw the comments and trailers. I like the trailers, but some people say that the movie's completely different from the books. Take the scene of Medusa appearing from Percy Jackson and the Lightning Thief. In the book, Medusa was first class ugly. In the movie, she was prettier than me. In the book, the three of them stay together. In the movie, the three get separated. In the movie, the only one's at Aunt Em's Garden Gnome Emporium were Percy, Annabeth and Grover. In the movie, there's a weird girl with them too. In the book, Medusa asks them to take a photo and THEN tries to kill them. In the movie, Annabeth and that weird girl run into Medusa and Medusa petrifies weird girl. In the book Medusa wears a ball gown and a VEIL over her face. In the movie, she wears something...um...attractive and she doesn't have a veil. There are a lot of other mistakes in this scene alone, but I can't mention them all. If I did, my brain would explode since I made myself mortal with omniscience.
Hope that was helpful!