I just finished reading UnWholly written by Neal Shusterman. UnWholly is the sequel to Unwind.
Although I enjoy series, I often think the best book of the series is the first book. I enjoyed Unwind, however, I LOVED UnWholly. I liked that the book continued the story of several of the main characters from the first book and also introduced a few new characters that should have an integral role in the third book. Although I found the book to be dark and actually had to put the book down and walk away from it at times, I really enjoyed the last 200 pages. My only frustration is having to wait until Fall of 2013 for the third book, UnSouled. 🙂