I have DC who has been there for a few years now. They are loving school. So many opportunities, so don't worry. My DC has played lots of sport and been in the junior and house drama productions (they aren't at all musical, sadly, but there are lots of opportunities there too). The art department is also fantastic.
There have been a few grumbles about phone policy, but the school are managing it and ensure children make the most of the opportunities on offer, so if you do have any issues/concerns do contact them. The head is keen to embrace changing technology, not ban it, but they do have a policy of when they can / can't use them in school.
The school is very hockey focused in winter (football 2nd) and cricket in the summer. They have been extremely successful in hockey. The focus may change with a new director of sport coming in September. I have heard from a two parents the same about sport, ie not getting into teams, but I think this happens across many schools. Everything will change with the new director of sport, but again contact them with any concerns.
No school is 100% perfect, but I haven't experienced any negatives at all, but obviously there will always be a few parents who may have. I am very happy with KGS. It's such a lovely school, not too big, the pastoral care is great. It's a lovely community. I've been very impressed with the leadership, both the head and the heads of years so far. Some very impressive people at the school! Their attitude to the well being of the children during lockdown has been very good.
It's a lovely school, with the right balance between academics, extra curricular and pastoral care. We came from state primary and were pleased to find so many down to earth families, I think maybe as they don't have a feeder prep school. That has been a big plus for us.
You will love the school, I'm sure.