I have never been in combat myself, but I have talked to many veterans and they all seem to agree that Saving Private Ryan has the most realistic battle scenes out of all the other war films. Also, there were a large amount of veterans who walked out during the film due to the gruesome nature of the first half-hour of the film.
Although Saving Private Ryan is unarguably accurate, I disagree it is the most accurate though because many other WWII films depict scenes that are relatively similar in setting and staging as Saving Private Ryan. A history teacher I used to have said the most accurate war film to illustrate the ferocity, gore and conditions of soldiers in war is the film Passchendaele.
Ofcourse though it is a subjective topic and hard to judge as the majority of viewers haven't participated in the wars depicted in films and the huge range of war chosen for films make it even more complicated.
Since in the beginning it had a point on the training. It had an American give german prisoners smokes then that american soldier shot the prisoners. It had many gruesome scenes. It was based on real people. Like one in it didn't shoot at all and just skulked for the entire battle. It has a scene where an American soldier 'loved up' a german local. Which probably happened or the producers just wanted a larger audience.
Don't get me wrong, I love this movie, I think the storyline is great and some of the effect are great considering its nearly 20 years old, however, the most realistic film, whether you can call it a real film, is "The Pacific". It was a great series and I believe it had the most realistic effects of any film i've ever seen in a film.