I read a lot of Heinlein's juveniles when I was younger, but I missed this one and it was on sale from Audible, so it was nice to enjoy one of his earlier works, before he started getting old and wanky. Everything from
Friday on was pretty much Heinlein getting his freak on, but his earlier novels are still sci-fi classics for good reason.
Starman Jones is your basic boys' adventure story: Max is a kid from Earth who runs away from home when his stepmother marries an abusive bum. He meets an amiable drifter who turns out to be a not-so-good Samaritan, but he meets the man again when they're both trying to find a way off-planet, and the two of them lie their away aboard a spaceship. From there, Max's talent for math and his inherent good nature and sense of decency lead him from one position to another aboard ship, and when the ship gets lost, taking a bad "jump" to an unknown star system, Max of course is the one who saves the day.
Obviously, this book was written for teenagers, but it stands up as pretty good adult SF even today, though it is a bit dated (it was written in 1951). The gender roles are pretty old-fashioned, and while Heinlein's FTL drives and beam weapons are standard sci-fi, you may chuckle when Max breaks out his slide rule to perform astrogation. Still, I think it compares favorably to any genre fiction written for kids today, and Heinlein did a much better job than most writers of bridging the gap between YA and adult fiction. I might not start with
Starman Jones if you haven't read any of Heinlein's juveniles before -- it's pretty good, but it's not his best -- but if you're already a Heinlein fan, this will definitely be an enjoyable read.