In the afterword, Spider Robinson describes how he came to read his first no-pictures "big boy" book, as his mother sent him to the library in Plainview, New York, and he returned with Rocketship Galileo by Robert A. Heinlein.
For me, it was Oakland, Iowa, Red Planet, and a couple of years difference; otherwise things were much the same. Spooky.
But Spider grew up to be a science fiction writer. And when an outline and notes were discovered for an embryonic Heinlein novel, he was commissioned to finish the work, and the result is now in print. And it's good!
The story is: boy meets girl, falls in love, discovers that girl is the granddaughter of the richest man on earth. Annoyed at the deception, he catches a ride on a colonizing starship. Then troubles really start.
Although Heinlein apparently meant this as one of his juveniles, there are enough dirty words and adult situations here to (I think) disqualify it for that status. Folks acquainted with the RAH oeuvre will recognize plot elements from Time for the Stars.
There's lots of Spiderly wordplay, and that can wear on one a bit, even on one whose blog is named Pun Salad. I also detected a number of amusing inside jokes and references to other Heinlein works, but I wouldn't be surprised if I'd caught only a small fraction of them.
In short, a great read; it really is like having a new Heinlein novel to read, and Spider Robinson has my heartfelt admiration and gratitude.