Although my classmate beat me to this book in the 50 Book Challenge, I was apparently the first person to check it out from the Harvard library system. Incidentally, I miss the days of checking out books with hand-written cards that allowed you to see who read the book before you and how many times your obsession with a given book has led to you to check it out. But I digress.
Scalzi's book is a fast paced, single serving read packed with realistic characterization and in possession of a differentiates voice. His debt to Heinlein is obvious, but the story line is more complex than many of RH's early works. There were several bits where I laughed or exclaimed out loud - Scalzi's a clever fellow, and his humor lightened what could have been a rather gloomy story.
I can see how a writer with a political axe to grind might find the world Scalzi's created appalling - why overpopulation needs to be solved by interstellar colonization rather than more conventional family planning methods puzzled me - but he does a good job of accentuating the humanity of humans involved in a multiverse-wide struggle for survival. I couldn't put the book down, for which I will pay dearly in my four hours of class today.