This is one of those books with a fascinating story idea, but where the implementation might just not be for me. The first two third of the book are so full of technical description that I spaced out multiply times waiting for the story to continue. The, to me, most interesting last third of the book could have gone on much longer. It cut off at a point where I really wanted to know how humanity goes on. How will they handle the new found races on earth? So it left me rather unsatisfied (and glad that I've finally finished).