Heinlein did not write very many fantasy works, but when he did, the result was usually a rather different and fun romp. Glory Road is probably his best work in this genre, and it makes most other sword-and-sorcery stories pale in comparison.
Oscar, our hero, is a Vietnam veteran idling away his time on the Isle du Levant, a small island off the coast of France known for its lack of haute couture (or clothing of any style), when his eye is caught by the most beautiful woman he has ever seen, sleekly muscled and with regal bearing. When she offers him a job with `great adventure and great risk' he blindly accepts, little realizing just what an incredible jaunt he has let himself in for. A journey that will travel through some of the 20 universes that Star is Empress of, on a quest to retrieve the stolen Great Egg. Along the way you will be treated to a sword/bow and arrow fight with a very real set of dragons (with a rather amusing fight strategy), a hand to hand fight with a very dirty (and smelly) giant, pentagrams and spells for magical flight. All of the incidents along this trip are treated with a fair dollop of humor and satire (and at least a partial parody of other sword & sorcery epics such as Conan the Barbarian), while at the same time Heinlein manages to present some pseudo-scientific explanations for the `magical' incidents, something he did in just about all of his fantasy works, so that it is somewhat problematic to call this a `fantasy'.
The climatic sword battle with the `Eater of Souls' is very different from the standard hack-and-slash portrayal of sword fights in all too many movies and novels. Heinlein was a member of the fencing team during his time at Annapolis (for some possible reasons for why he took up this sport, see the "Lazy Man" portion of Time Enough for Love), and this experience and knowledge is directly transposed to the battle descriptions of this book, making for a very fascinating and exciting read.
But there is more to this book than just a fun trip down the yellow brick road of swash-buckling heroes and dragons. Oscar is not your typical mighty-thewed simple-minded adventurer, but is rather a man who thinks about his actions, who has a strong sense of moral responsibility, who can (at least intellectually) comprehend that customs change with different cultures, a true hero who understands the need for noblesse oblige. Nor is Star a simpering damsel-in-distress, but rather a hard, practical, self-reliant, intelligent and rather commanding woman. The interaction between these two strong characters forms the starting point for Heinlein's exploration of how relations between the sexes is defined by cultural biases and expectations, the individual's own sense of self-worth, the ability to communicate and compromise, and the problems that married couples face. This philosophical type of discourse occupies a good portion of the last third of the novel, and may not seem at first glance to be well integrated with the first two-third's emphasis on action. But on reflection, the last third forms the completion of the thematic structure of the work, whose groundwork is well laid in the first portion, and provides a level of meaning that is not common in fantasy works.
Of course, this being a Heinlein novel, expect to find some sharp remarks about the IRS and taxes, how to fight (and not fight) a war, status symbols, horse racing and lotteries, laws about carrying greater than six inch blades in public, veteran's benefits, Congressional methods of making laws, the bizarre workings of military organizations, the relative strengths and weaknesses of democracy versus monarchies and feudal structures, and under-the-table tactics for motivating an individual. As always, Heinlein will make you think about and question your own opinions and assumptions on these things, even if you don't agree with his expressed viewpoint, as he always makes his viewpoint at least sound logical and correct.
Read this one for the fun and humor. Then let it soak in and expand your sense of the possible, the correct, the moral, and the reason for living.