I signed up with Greenheart Travel's high school abroad Austria program for my gap year before college-- living abroad for around ten months. Yes, I was technically with Greenheart, but I was mainly under their partner program, STS; which was a whole other mess-- but that's a story for another time. I would say overall there was decent planning on Greenheart's part. You could tell the organizers of STS obviously had it in for the money, were very disorganized, and literally did no research on any of the host families before placing the students. I also don't know how some of the families make it past the approval check, considering the amount of horror stories I've heard and experienced. Despite the poor organization skills of their counterpart, Greenheart Travel was very supportive when issues arose, and continued to have an open ear about your time abroad when I got back. I feel every program has their ups and downs for sure, since you are considered a liability when abroad with an organization. I would recommend going abroad with a youth centered program if you are used to structure and rules-- if not, I'd recommend going and studying at a university or living in your country of choice on your own.
Besides the downs of my time abroad, living abroad was an indescribably AMAZING experience. I learned so much about not only another culture, but about myself. You meet so many people from different backgrounds as yourself- exchange students and natives- with whom you'll probably keep in contact with long after your exchange is over. I would never take my experience back. In fact, it has only encouraged me to go abroad again and learn more about the world around me.