I boarded from 5-18, as a weekly boarder until the age of 11 and then a term boarder after that. I didn't dislike the experience. All the cool things happened at weekends and so if you weren't there you missed out on the action . And I made some life-long friends.
But while a lot of people have touched on the impact it has on the child at the time, I don't think anyone has mentioned the impact it has on the relationship between child/parents even into adulthood.
When you go to boarding school you learn to be independent. so as a result I am now fiercely independent. If I was sad/upset I would talk to my friends, maybe even a teacher I trusted, but never my parents because they were hundreds of miles away. And so as an adult I never had that relationship where I could go to my mum with anything so I still can't now.
I never experienced what it was like to come home at the end of the school day and be at home with my mummy and daddy - even as a 5 year old.
My birthday was always at school and so was never special.
My sister didn't board so she had all these things that i didn't. And she is now very close to my parents, pops round all the time/they look after her kids etc but I don't feel I have that - I don't feel as if my parents home is my home in the same way she does, iyswim?
I could never do it to my child, and I do think that parents that consider it as a long-term option should seriously consider the implications, even into adulthood.