I haven't heard anything about the 2005 book, no. Quammen has a penchant for vivid - sometimes lurid or even vulgar - imagery, so if that's a turnoff that might be a problem. Still, I found the earlier book very informative. (And entertaining; the story of Darwin and the iguana really struck me funny.)

As for Janus: yes, I noticed that too. At one point I was concerned that Rowan seemed to be making the same mistakes as before. She turned suspicious faster than I expected, though. Kirstein's characters actually do seem to learn from experience... I'm looking forward to the next book.