a) Mr. Upgren did not harp on the dark-skies issue in many of the chapters, and adding up to about 1/4 of the book. Granted, I think he's right about the uselessness of outdoor lighting wasting energy to the night sky. However, he goes way overboard on this, to great detriment of the book. It could have been in one epilogue chapter at the end.
b) the author explained what the turtles have to do with the rest of the book cause it's not really clear to me (oh, yeah they can navigate pretty well in dark skies, whoopeee!).
c) the writing were of the quality of Arthur C. Clark. It's not, but pretty readable anyway.
I did note that the basic math, on distances to the horizon, center of mass of earth/moon system, etc. seemed right. In fact, I noted no math/numerical errors, which is amazing in and of itself.
Very interesting; just ignore the preaching about the streetlights.