I don't get it. Very much at the beginning of the movie a paraplegic army recruiter proudly proclaims: "Mobile infantry made me the man I am today." How can anyone take that at face value?
As satire the brilliant part about that, and a few of the other really shocking things like the drill sergeant beating up a new recruit to establish himself as head of the pack, or the whipping, is that it's lifted fairly directly from the book. A subset of the fans of the book get mad because the violence and fascism seemed so much cooler in their heads. Other fans recognize that Heinlein's books were to some degree…
For example, later on in the book and the movie, a recruit asks why they learn to throw knives when guns make them obsolete. In the book, the sergeant gives an explanation of tradition and admits that knife throwing is a fairly useless skill for mobile gundam suit pilots. In the movie, the sergeant just throws the knife at the cadet's hand. Towards the end of the book it's revealed that drill sergeants are carefully screened not to be sadistic jerks, but to actually be decent people who are carefully calculating the best way to train their cadets.
The book was well thought out. The movie was just stereotype and mockery.