Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Vintage Sci-fi, almost as good as Jannisaries series

I've read this story 5 times. It is an excellent book as most of his books are. Solid storyline. I highly recommend this for beginning sci-fi readers. Almost as good as Heinlien, and that is high praise indeed. I also recommend Footfall, Lucifer's Hammer, Mote in God's Eye series, King David's Spaceship, the Falkenberg series and the Janissaries series