It did not take long for me to get engrossed in this book. I picked it up last night figuring I'd read a few pages to get started before going to sleep. I was hooked - I read more than half the book before my body disobeyed me and fell asleep.
I loved the characters of John Perry and The Old Farts. It's not a comedy by any stretch of the mind, but Scalzi has given the characters a wry sense of humor that really made me laugh and connect with them.
This is apparently the first book in a trilogy but I would never have guessed that after reading it - it is a complete story on its own.
I've seen a lot of comparisons between this and The Forever War. That book is sitting on my shelf, but I think I had better wait a while to read it so that one doesn't influence my opinion of the other too much.