Instruct: Classify Amazon reviews into positive or negative sentiment
Query: excellent book, very entertaining

This is an entertaining young adult novel about twins who discover alien disks that allow them to become historical figures for a short time. Ryan especially loves the disks, and begins to use them almost like drugs to escape from his screw-up life, while his twin sister Taylor tries to keep him out of trouble. The book is fast-paced and, in places, funny; the twins are likable and believable. The most engaging character is Ellis, a friend of the twins.I have a few minor quibbles with the book, the most important being with the ending. The McKenzies have some family problems, and we don't see these get resolved by the conclusion of the book, yet we are clearly supposed to believe that the final confrontation provides a way out of the family difficulties. But the young people themselves discover some truths about life and their own identities, and do it in an interesting way.