Glory Road's one of the very few Heinlein novels (the only other one is Magic, Inc as far as I know) that wander into fantasy territory, although the parallel-worlds thesis is prominently invoked to provide some sort of practical grounding for it all. It's a fantasy-ed up version of the sort of action-packed protagonist-centered tale Heinlein was at his best with. His humourous bits can be a bit dicey, but there are a few good gags. The characters may not be very realistic, but they are so vivid and in-your-face that they come alive for the duration. There's a lot of the usual railing against popular democracy and a few examinations of sexual mores along the way, a spanking scene (something that sadly became increasingly mandatory in Heinlein's books) and only one orgy, for a change. Two really, but our hero only participates in one. The actual plot is a bit slight - modern-day Ocar Gordon is recruited by a beautiful woman to go on a perilous quest, defeats a few preliminary monsters, tackles the big challenge and rescues the desired artifact, marries the woman (who turns out to be the person in charge of the multiple worlds), gets bored, lumbers around back on Earth for a while, and then decides the time has come to set out on that old Glory Road again. Still, it was a fun book. Heinlein clearly had fun writing it, even if he didn't go on to make a habit of working in a fantasy vein, and it's hard not have fun reading it.