This is my favorite Heinlein book and I just reread it after probably 20 years; still love it, although I now see it as a bit more oversimplified and idealistic than I did back then. Still, Mike is a likeable, sympathetic, and poignant character and the hypothetical society and situation of the moon colony are very well described. Although there is a strong political theme as with many Heinlein books, it's not out of place or forced in the setting of this book, and his idea of line marriages is actually quite interesting. Also as usual with Heinlein the characters are a little two-dimensional, but it's still a remarkable book particularly given its age. On this rereading I found myself wishing it were a longer book with more detail; I was sad to come to the end again so soon. I've read an extensive amount of Heinlein and although I've enjoyed many of his other books too, this remains my #1 favorite of them all (mainly because of Mike).