This is one of my absolute favourite TV shows ever! Each episode always makes me actually laugh out loud. The kids do smoke pot (they don't show it directly but it's heavily implied), have sex (again, not shown but really implied), drink underage, and make a lot of jokes about sex and things like that. But I think that those things are what makes the show so believably 70s and kind of relatable for teens (not that all teens can relate to things like that, just that it makes it seem so much realer). Since it is a comedy, it doesn't really take things like teen pregnancy and other more serious issues super seriously, but it does at least get a bit more serious than usual. This show is very light and funny, and is the perfect show for a good laugh. It's also a nice break from all of those teen dramas. Also it's on Netflix!
Teens should be fine watching this, it's no worse than most things talked about at school. It seems a bit ridiculous all of the parents recommending no teens at all watch this, because teens are going to know not to do everything they see on TV, and that doing things like pot or sex are not a good idea. Parents, trust your teens a bit! Although I understand where they're coming from, this show gets a bit risky at times, I think that 17+ is a bit extreme. 13+ is more reasonable, but it all depends on maturity I guess. :)