I went from aged 11-18 in late 80"s / early 90's it was a real mixed bag. Some days I absolutely loved it and other days I just wanted to be at home.
The dislikes for me were having to share a dorm. There were between 4-8 teen girls per dorm until 6th form.
The reality is it is not like an Enid Blyton school story, where everyone is having fun, are great friends always and having midnight feasts. The novelty of sharing a dorm, having very little space of your own or any privacy really soon wears off!
Yes, I had fun with friends at times, but the drama when there was a friendship fall out or if another girl had a crush on another girl that someone else liked was crazy.
Also disliked having timed showers and baths ( 5 and 10 mins ) and only being able to speak with my parents once or twice a week during phone time. This was in the days before mobiles, so everyone around you could hear your conversations Also hated the fact that older girls used to choose a younger girl to be their dogs body, e.g. you'd have to make their bed every day, change their bedding weekly etc. This was seen as being perfectly okay in the name of tradition.
i loved the sporting opportunities, the independence that it taught me, most of my lessons and teachers, the food and exeat weekends.
you also always have to be on. If you were homesick you had just bury those feelings and get on with it, which is so emotionally unhealthy and wrong!