I rather liked Battle Royale, I do however understand a lot of peoples complaints about it. The art for one thing, it's nor my favorite style, too western looking for japanese kids to be honest, but you can't really argue that it is not well drawn. I think that the caricature look of it I liked on the other hand, for the same reason I enjoyed a lot of the slightly super human stunts, especially by Kiriyama, and to some extent the gore as well. I'll tell you this, I'm not a genral gore fan, most of the time and a lot of the time here as well I just find it disgusting and unecessary. But what is the feeling of this manga? I think the caricatures, the gross out factor and the supernatural aspects just brings you there. How much more horrible wouldn't a bullet to the face of a person standing right next to you rather than a picture of it be?
As for the story I rather enjoyed it as well, and to be honest rather than a story it is about characters, and how these characters react to this extreme situation. The backstories I think makes the chracters come alive, they are not just another kill, another messy death, they are made into people with interests, feelings (well most of them) and friends. Which of course is what makes this manga so disturbing, and don't get me wrong, I do think it is. And I'm certain it was meant to be as well.
As for how realistic the peple and their backstories were, I think most of the chracters in were very realistic, what you have to realize is that all these people are put in a very extreme situation, it is made very clear to them that it really is kill or be killed by seeing some of their class mates killed right in front of them. And two, they come from a very different society, I don't think it was made as clear by the manga as it was by the novel, but it takes place in a very different present (one which I always imagined is the result from world war two ending differently) where "the program" has existed for 60 years and the nation is at war or something similar to the cold war at the very least. And there is only 2 people that are really activily killing, most do it in self defence, out of extreme fear for their own lives or out of insanity, which I think is entierly plausible given the circumstances. In the end, I wouldn't say I could relate to but clearly understand most of the characters in the plot, though some may be the protagonist or antagonist a bit too much to the core, but once again I think it sort of brings, if not them, but their action alive, it can really make you feel what the others around them must feel towards them.
This being said, I have not given this a perfect grade, for several reasons, the manga and the novel along with it was pulp litterature, it was an easy read, while still making you think, which is always a good thing. Some times I think the violence took too big a part over shadowing the chracters afflicted by it. A plot hole here and there. But my main issue with the manga was the, what seemed to be almost constant, nudity. Don't get me wrong, I'm no prude rather too far in the other direction, but I just didn't feel it belonged there, and many times it just felt stupid, really stupid.
But I still really liked it, in my opinion it has a lot of believable chracters which i could really feel for, and a lot of suspense and very original writing in some scenes made for an exciting read even though it kind of messed me up emotionally for some time after reading it.