Gantz is a tense, emotion wringing story with a lot of blood and a side portion of sex. Unless you are very tolerant of hardship, blood and sex this isn't for young children. Parents won't want their children to watch these episodes until they are 18, teenagers will love watching the show when they are 15 and perhaps even a bit younger and will miraculously be totally unharmed except being exposed to a couple of interesting ideas.
Ideas (certainly not comprehensive):
1) What happens after you die could be Heaven or Hell, could be nothing, or it could be something else entirely that no one has considered before
2) Young men tend to be more horny than have sense. (Amazing how for some reason this just isn't projected most times there are teenagers around)
3) Materialist idea of 'you' or 'I'. It appears that almost all of the characters in the show are 'captured' at the time of their death and recorded and transported to Gantz. This either implies that the soul is recordable and recreatable or that the soul is unnecessary in the recreation of a person.
4) The weaponry appears to be fairly original.
Kei Kurono is certainly the most interesting character in the series. He can be annoying and is certainly obsessed with sex, but I think that merely makes him a relatively accurrate depiction of a teenage male.
One of the key points in this very violent series is that violence is real and although the activities in the Gantz games are certainly violent, you can't get away from violence even in a place that should be safe like home. This is demonstrated by Kato's little brother being beaten by their Aunt that is taking care of them because their parents are dead.
The effects of violence at home, rather than violence in the Gantz activities are what appear to motivate Kato to incredible rages. Kato, who is the most reasoning character in the series. Kato, who is unable to kill in order to survive or even protect his friends - is driven by the violence at home and school to beat people insensible.
The series is neat. Not all questions are answered in the first series. Nor, I suspect are they answered completely in the second season. Some questions perhaps we do not have the answers. Some answers are held in the Manga and possibly Japanese Anime versions of the show.
I hope they continue to produce Gantz Anime, and perhaps some of those answers will be revealed. Perhaps it will be like the original Guyver series. One of the best Anime I've watched and I was horrified that the end, was in fact the end. Clearly a show (just as Gantz) that there is plently of material to continue the story.
While I'd love to continue reading the story in the Manga, it appears to currently not be available in English.
I will hope that people will be able to watch this show and not be put off by the sex and violence contained within it - just as they are contained in real life. It certainly provided me with a nice diversion.
Oh, and yes, I hate the fact that there are only 2 episodes per disk. Who makes that kind of decision? I have anime with 5 episodes per disk, 2 episodes per disk but most commonly 4 episodes per disk.
Don't waste resources people! 13 episodes could have easily fit on 3 disks compared to 6! The extra disks, cost to the manufacturer, extra materials for disk holders and the large box - man - it just makes sense to shave some cents off the cost of the series and sell it for the same amount and make more money than waste all those disks with 2 episodes each.
Blech. Good thing I really like the series.
Atheists, agnostics and secular humanists will probably enjoy this series as well as people who are fairly moderate in temperance.
Folks that take their religion too seriously, don't like anime, don't like sex or feel that there is too much violence on TV - need not apply.
Funny how this is a Japanese animation, with so much blood, guts and sex and they have lower incidences of violence in their country than in the USA. Must not be the violence and sex on TV that causes the problems, folks! If blood, guts and sex on TV causes it in reality then Japan must be overrun with roving gangs, rapes and thousands of murders, but we know this is not true.