I think this show is pretty entertaining to watch, but it doesn't really teach you anything. It is a shame, because a show like this could have been made much better, and much more realistic.
The characters are pretty stereotypical, as others have pointed out as well. There aren't much depth to the characters, and they aren't developed well enough. A really good show or movie manages to portray their characters and let them grow so that they almost come to life in the eyes of the viewer. I like to watch shows where I can almost regard the characters as real people - that's when they become realistic and you can begin to sympathize with them. (I have watched shows/films where the characters have been so vividly portrayed that I almost have to remind myself that they don't exist in real life, and just thinking of their non-existence feels strange, because they feel so real.) But, this does not apply to The Secret Life of the American Teenager.
Sex is a very important topic in this show, and everyone seems to be talking about it, or doing it, all the time. It is at times even to such an extent that it begins to feel a bit unrealistic. In the real world, teenagers aren't this obsessed with the pure thought of sex; and neither are adults. The teenage characters seem to taking on very adult things, and yet they all seem to be very naive and immature. Which is also why I find it odd that the parents are so laid-back when it comes to all of this. None of the parents really seem to mind that their kids are in serious relationships or having sex - and even those who react don't do it in the way that you'd expect.
I'm not an obsessive follower of this show, but I do watch it sometimes when I have nothing else I'd rather watch. So I like it, but it doesn't give me anything, if you know what I mean. I don't walk away from having watched an episode feeling like I have learned something, or realized something. It is very clear that this is all fiction, and unrealistic fiction at that - meaning it is hard to truly "get into it".
I don't think kids and tweens should watch this because of its adult themes - and the fact that the unrealistic, unhealthy (and slightly obsessive) portrayal of sex that it displays in all of the characters is not something you want your kids to learn and regard as truth. Older teenagers who have had sexual education in school (or from their parents) may be able to watch this from the entertainment aspect, without taking the values and morals about sex to heart. Teens who have real-life experience from high school will hopefully realize that this is not how things work in real life.
