I lived in San Jose de la Mariquina, a small town near Valdivia, and taught English at a local school for 3 months in 2018 (April-July). The program was initially arranged through Greenheart, but once I arrived in Chile, all of the support was handled through their Chilean partner organization, Experiment. Everything went smoothly and the folks from Experiment were friendly and readily available via email. I had no formal classroom teaching experience beforehand, but the week-long orientation at the start of the program helped me feel prepared. I worked in a school that serves students of all ages, from per-K through high school, so each day was different and I was definitely never bored. The kids were adorable and excited to have me in their school.
I was lucky to be placed with an awesome host family and had a great time living in my small community. There was another American teacher in my town and we frequented the handful of cafes and bars together after school and made a band of Chilean friends. The closest big city, Valdivia, was a 1 hour bus ride away, so having a social life really depended on integrating with the locals—which ended up being great because it forced me to improve my Spanish. I think the key to this program is having an open mind and being flexible, because you could really end up anywhere in the country, from a small town to a big city, and with any type of family. Chile is huge, and although I managed to take a good number of weekend trips, I feel like I only scratched the surface in getting to know the country. I imagine others will have an entirely different experience from me depending on their placements!
I'd say the one downside of this program is the cost. You earn a small stipend while teaching, but it is not nearly enough to replace initial program fee. If you are interested in traveling on the weekends, it is essential to come with extra savings. That being said, I wouldn't trade my experience for anything. But if earning money is a priority for you, this program probably isn't a fit.