The book is, in my opinion, quite good and the movie only barely scratches the surface of it. While it's pretty short it does go into much more detail about the world, in general, than the movie does and doesn't have any of the Fascist overtones of the movie. In the book there's no Dizzy, or Doogy Houser, and Carmen is barely in it, but in return you get much more focus on Rico and his training as well as the Mobile Infantry.
Dizzy was a throwaway character in the first chapter. Male. Not someone Johnnie went to school with or was in Basic with
or was in any way romantically entangled with. Carl (Doogie)
was a friend all through school and they
did join up at the same time, and he
did go on to weapons development, and that was the last he appeared in the book (barring a mention when his base was wiped out by the Bugs). Carmen is in it a bit more, but we don't see her after she visits Johnnie while he's in OCS on her way to her new posting.
The Hero's Journey in the book, with a lot of sociopolitical introspection, is how Johnnie goes from not planning to join up* to volunteering for reasons he doesn't really understant yet himself to finding himself in the infantry because he doesn't really have any of the advanced training or skill at maths that would have landed him in more specialized service, through some personal tribulations and revlations, to going career and becoming an officer. It's a gem of what poli-sci wonks call "Heinleinian Libertarianism". That is, political power is granted those who have demonstrated a sense of personal civic responsibility, and individual freedom exists within a political framework to lubricate what happens when one person's individual freedom rubs up against another's. I don't feel he's all the way there, but it
was written in the 1950s, and I feel it is a stronger starting point than many other social/political models.
[*
Civilians have plenty of rights and privileges, can own land, start businesses, etc., but to vote or hold political office, one has to be a Citizen -- that is, satisfactorily complete a minimum-two-year term of government service. Not necessarily military, but that's what the book focuses on, because that's the route Johnnie went.]
He wasn't from Buenos Aires, he wasn't European. He was Filipino, from the Phillipines. He didn't really have much interest in Buenos Aires being destroyed until he found out his parents had been there at the time on one of his father's business trips.
And one thing I
really want in any new adaptation, I'll just leave here:
Those familiar with the book will get it. Each troop transport had a bit of a song they'd play to recall personnel. The one Johnnie spent the most time on was the
Rodger Young, and its recall tune was taken from the Ballad.
"
To the everlasting glory of the infantry
Shines the name, shines the name of Rodger Young..."
--Jonah