I liked Penumbra when I read it… unfortunately that was a quite a few months ago so my memory of it was a little rusty. As such, my contribution to the discussion was minimal besides providing some fun facts about the book’s author and background. (For example, although the book features Google heavily, Sloan used to work at Twitter.)
As for the others, it seemed most of them enjoyed the book. That is except for one notable exception who felt it was quite the Google propaganda. The rest weren’t bothered by it and liked the story even if they felt some of the plot went a little slowly. I personally appreciated the intersection between technology and old school books. All in all, well received.
Now we just await the announcement of our next book club pick.