I was an exchange student in hugh school and in university, and really, those are two completely different experiences and I recommend both.
In high school, I really got to take a dive and soak up all of the culture, family life and so on. I lived with a family, had siblings and parents, so to say. I went to school and was pretty worry-free, to be honest. it was amazing. And hard. And exhausting. And rewarding.
In university, I was on my own. I had an appartment I shared with some other students, but it wasn't all that easy getting to know "locals". A lot of exchange students end up hanging around with each other (I also observed this in my own University back home).
Only caveat:
going to Canada on an exchange in 1995 caused me to become German in 2011.
I met my now-husband there.
...we're going to never let our daughter talk with any foreigners, ever ;-)