I always thought Rambo, in every incarnation was dreadful. It wasn't until many years after it was released that I discovered that it was thoroughly bogus, in addition to being an artistic nightmare. Like so many Vietnam veteran movies, it brought attention (or reinforced attention) to an omnipresent condition that simply doesn't exist, now or ever, except in extremely rare cases. I'm willing to wager the (PTSD) condition is 100% nonexistent among Special Forces veterans (Seals, Green Berets etc.).
Leaving aside the question of the veracity of PTSD, 'First Blood' was a good action film with a great feeling for small town America and the tension between Vietnam Vets and the general public at the time. By the way, didn't they used to call PTSD, Shell Shock? That was WW1. In WW2 they called it Battle Fatigue. In Vietnam, PTSD... Language gets more and more distended...
Like said, Rambo only works if you see it as pure fantasy, something going on in the head of the lead character. It would explain why they have the bad guys dressed in Japanese army uniforms, and why at the end, instead of shooting Charlie Napier, he blows away the computer (symbolic of the individual's resistance against the impersonal, mechanized military-industrial complex, blah blah, blah, blablah, blah). If Paul Verhoeven made the exact same film, people might recognize it as being a satirical (or something close to it) fantasy.