I can speak from two generations of the reality and differences of the movie. My dad was at Parris Island in '74 and the stories he told me BEFORE he saw the movie were spot on. He told me about Gardener, the "shitbird", and the ex highschool lineman that tried to hit the DI the first day and got his teeth kicked in by the DI. He also told me about the other shitbirds that were given the option of The Corps or jail time and how the US needed "warm bodies" at the time. He told me about a very similar speech a DI gave them about supplying God with souls and holding a Bhudda statue and getting them to warface chant "Bbbhhuuudddaaa" over and over again. They were called every name in the book, got the physical shit kicked outta them, and had to cover for each other (dad had to qualify shoot for Gardener by rolling over to his mat and firing- dad was sharpshooter). Dad's least favorite PT is still the sand buckets lol.
My experience with Army Basic was pretty different. Most guys there were pretty decided in their focus of military career as opposed to just being warm body ground fodder. "I'm just here to learn computers" was pretty common, at least in my group. Luckily the US wasn't really engaged in any major foreign engagements at the time, so it was really maintenance by SF and presence at NATO bases at the time

Our TIs weren't there to hold our hands, but they weren't allowed to do many of the things in FMJ due to our wonderful litigious society with the asshats at the ACLU. They couldn't hit us or call us faggots (maggots has been used at least since my dad's time as an alternative). Again it was a different time. We had two shitbirds in my group (now just called fatbodies) but one actually washed out thankfully. I had experience as a Boy Scout, so it was really like a Mean Crazy Summer Camp with a Gun for me. I had always been into the military so I had read many things previously that I got to actually touch. I had also done JROTC in highschool so drills weren't a problem. I'm pretty bright, but those things always mess me up so I'm glad I had practice lol. As I mentioned before I was pretty much there for a career with rank boosts from Eagle Scout and JROTC. I got my knowledge, served my time happily and met many great friends I still have today. There is something about the military, when you are doing things in a routine fashion that many folks never ever get to do, that you take a step back and say "Holy cow. Me and these 23 other assholes just changed X event from changing the WORLD."
So yeah for the time period it is spot on. I emailed the 10 mins of boot camp to dad after he got retired from his job from a stroke. He called me all choked up, but he was talking about going out and finishing the roof of the house. Mom later said he had watched it several times in a row and had of course forwarded it to everyone on his email list- but it was the catalyst for getting him back to normal awesome guy again

I'm glad to say that he is completely recovered and enjoys his Saturdays with his granddaughter and he is STILL "Dead Eye Atticus" if any of ya are a lil read up

This is my account some first hand, some not, hope it helps someone. Thanks for reading