I am writing this while still in Italy, having just completed my 10 weeks of teaching in Verbania, Italy. I could not recommend this program enough.
Greenheart provides incredible support and preparation, and the orientation we received was thorough. Orientation was also a blast because I was able to meet the other 20 teachers also being placed in the Piedmont region (most of them near Turin). Everyone was instant, effortless friends and all of my trips around Italy on the weekends involved at least one of these new friends, sometimes more (like the 10 of us who took on Florence for a weekend---such a blast).
I had 2 host families during my stay, and each one was fantastic. I consider them close friends now and living in their homes meant traveling with them to their favorite local spots, eating incredible meals together, and sharing our worldly perspectives around the dinner table over local wine. Staying with host families was certainly the most rewarding part of this adventure as I feel I got a very deep sense of Italy culture.
Teaching at the local middle school was a really great experience. It boosted my future teaching career so much. And, be warned, Italian school systems are very disorganized. If you can go with the flow, you'll be okay. That being said, be prepared to run an entire class by yourself because the teacher usually with you took the day off to go skiing. Be prepared for teachers who harshly yell at students and students who yell right back. It's a different system in a different culture so be prepared for it to take a lot of time and energy.
During my time, I've been able to travel to Florence, Venice (for Carnival no less), Naples, Rome, Genoa, Turin, Milan, and even into the Swiss Alps. Every day is an adventure and a chance to eat the most incredible food you've ever had in your life. And the gelato is so good, you'll seek out the best places in every town and have it at least 3 times a week. Embrace it.
I highly recommend this program for anyone who wants to be immersed in a culture, work hard at school, eat amazing food, and travel around Italy/Europe. I never had any issues.