I have previously discussed Heinlein in general, but quite a few of his book are worth specific discussion.
Have Spacesuit, Will Travel is one of Robert Heinlein's "juvenile" novels, written for a younger audience and published by Scribner's. All of the juveniles were written during what I consider Heinlein's peak years; his writing in these books is invariably tight, engaging, and fast-moving, even when nothing active is apparently happening. Of the juveniles, I (and many others) tend to put two consistently near or at the top: Have Spacesuit, Will Travel and Citizen of the Galaxy.
Have Spacesuit, Will Travel is chiefly the story of Kip (Clifford) Russell, a young man with dreams of space travel in what is, to modern eyes, a rather retro-future – one with regular flights to the Moon and beyond, atomic rockets also plying suborbital routes for fast travel around the globe, yet no pocket phones or computers we would recognize, and an apparent culture somewhere around 1955; in addition to the protagonist's employment as a "soda jerk" (counter tender in a 1950s soda fountain), one of the major plot drivers is a contest to devise a motto for "Skyway Soap".
Kip's family is also peculiar; his father appears to spend most of his time reading, with money coming in via royalties. However, like many Heinlein characters, he has a very strong opinion of the need for hard-edged scientific education, and when he discovers that Kip's school is practially a parody of the liberal feel-good school of the late 50s-early 60s visions, he points out that while Kip COULD get excellent grades this way, it will teach him nothing and in the end get him nowhere. Kip's mother doesn't make much of an appearance (not uncommon in this era), although she seems willing to support anything that Kip feels he really wants to do.
While contests to find a company motto could be envisioned today, it's unlikely anyone would expect it to involve people literally writing the motto on the wrapper of a soap bar and sending it in, but that's exactly what the Skyway Soap competition involves. Kip throws himself into the contest with iron determination because the first prize is an all-expenses paid trip to the moon. He sells soap, he gives soap away, he buys soap, all to get the wrappers so he can send in more and more mottos or tag lines – thousands of them.
When the winner is announced, Kip hears one of his mottos recited word for word… and then sees another person walk on stage to claim the grand prize, because several people submitted the winning entry; the actual winner was then decided by the time of reception: "Beaten by a postmark. A postmark!"
But there are runner-up prizes, and Kip receives his: an actual spacesuit, previously used on the Moon. At first disappointed, Kip quickly shakes off the mood and decides to devote the same energy to restoring the spacesuit to factory-new condition – including water, food, air system, emergency drug supply, and all. After many weeks, he succeeds; the suit is back to full operating condition, as good as new.
And as he's walking along, testing it and enjoying the flawless functioning of something he restored from almost junk… he gets a distress call on the suit radio. A spaceship of unknown type lands near him, but the people calling for help are fleeing from powerful enemies, who recapture them along with Kip.
So begins Kip's real adventure – which will take him to the sterile beauty of the Moon and far, far beyond, into conflict with vile alien invaders and under trial by cold, analytical councils beyond the stars.
Have Spacesuit, Will Travel showcases much of Heinlein's respect for and promotion of scientific and engineering knowledge. The protagonist makes use of much of his education during his adventures, ranging from the repair of the suit to calculating the distances a constant-acceleration vessel might be going. Kip gains a companion, a little girl simply called "Peewee", who is also a certified genius. This is not an unusual Heinlein approach; several of his main characters are overshadowed intellectually by other characters, partly I think to make the main character's often multifaceted talents seem less wish-fulfillment in comparison.
This is often also just appearance, not actuality; when Kip ends up talking to Peewee's father, Dr. Reisfeld – a very famous scientist in his own right – he is told that Reisfeld knew Kip's father, a scientist who married his own brightest student: "I doubt that their offspring is any less bright than my own." Kip's swift mastery of very hard academic subjects on his own, plus his figuring out the complex engineering and practical approaches needed to restore the spacesuit (which Kip whimsically nicknames "Oscar", a name that shows up more than once in Heinlein's work) are clear markers of an extremely capable young man.
The book is very fun, at turns humorous, tense, and exciting. Unlike some Heinleinian heroes, Kip does not by himself deal with any of the major problems, although his efforts are instrumental in saving him, Peewee, and the alien simply called "the Mother Thing" who is their major ally against the invaders. This is another of the traits which helps keep Kip from becoming a Mary-Sueish character; the problems are addressed by others or by teamwork, not by the heroic actions of the main character alone.
Have Spacesuit, Will Travel is still a fun read today. Read to modern readers, it's also a glimpse of attitudes, behaviors, technological assumptions, and other elements – both good and bad – of an era which is now as far in the past for today's youth as World War I was to me when I read it. As such, it's not just a fun story, it's also a window to the past that is perhaps more fun to look through than a standard history text.
I still recommend this (and the other Heinlein Juveniles) strongly!