I really enjoyed this book. The concept of a man who had grown up on Mars and never seen another human until he was in his twenties is such a fun idea - and a rich canvas. Watching Mike try to grok humans gave a Heinlein great opportunities to point out some of faults - and our advantages.

I think my favorite part of this book is the word 'grok'. I would bet that there are deep discussions over the true meaning of this word - but I will contend that its closest meaning in English is 'to be enlightened about something'. If you grok God you have reached enlightenment. If you grok music you truly understand in the way that Mozart understood it. If you grok another person you love them. If you grok programming then you truly love and are really good at programming - that, and you're also a probably a pretty big nerd for using a word like 'grok' :) I used it in front of my girlfriend and she still hasn't forgiven me, since I had to explain that it was "a Martian word"!

One thing that I grokked (yes I'm going to keep using it dammit) after finishing this book is that it is kind of a 60's manifesto for free love. I wasn't alive in the 60's, but given everything I know about the 60's from movies, books, etc it seemed that my grokking was right.