This is what I like to refer to as a "knew them when" show. Mainly because it has so many actors who are famous today that weren't household names when they did the show. It had Hayden Christiensen pre-Anakin, Jewel Staite pre-Firefly (though with a dedicated fanbase, even then), Kyle Downes pre-Tudgeman, and AJ Cook pre-Final Destination and Criminal Minds.
That said, it doesn't mean that the show was bad. Far from it; it was a pretty groundbreaking for a show on cable. Every single character had a very deep and compelling storyline, from Peter's troubled past, to Sophie's endomitriosis, to each of the kids' several problems. It also didn't shy away from addressing teen issues like cutting and suicide, and even delved further into them to give possible insight at what might make a teen troubled. And it did so in a compelling manner that wasn't preachy (for the most part).
All in all, a very, very good and influential show that just happens to be a launching pad for quite a few promising careers.