I read this from start to finish over the weekend. It's a fast read to say the least. It was surprisingly well researched, smart, and thought-provoking. And so very readable. Who'd have thought learning about viruses, details on how brains works, what distinguishes lungs and gills, and so many other technical subjects could be so much fun! The action scenes are tremendous! The characters weren't wonderful but fine for the genre. The prologue wasn't great either. But overall this was a very exciting, speedy read; enthralling and engrossing and the pages JUST MOVE!! One weekend and it's over. My 15 year old's reading it now and he's riveted. Five stars.