Our daughter has been at Rose Hill from the Kindergarten to Y6 and she has been very happy there. It's a smaller school (in terms of number of pupils) compared to many other independent schools in the area, which I think is a plus.
They have great grounds and facilities, small class sizes and each child gets a lot of attention from teachers. All teachers seem to know the name of every single child and they have regular meetings discussing the progress of every child. The school is purpose built as a school rather than a converted mansion, which means it's not Harry Potter pretty, but in my opinion it's better organised and it's a better teaching environment that allows for 2 small forms they have in each year to sometimes learn and play together.
Also, I suspect that smaller portion of your fees will go towards maintaining an ancient, badly insulated property and looking after wast grounds than with some other independent schools. This means that more can be spent on actual teaching than heating and landscaping.
Looking back, there would be very few complaints we'd have about something, nothing major, but no school is perfect I guess and I'd expect that to be the case with any school.
Years 7 & 8 are very good value now and are essentially subsidised by all previous years fees. They historically had extremely small classes in Y7-8 (single digit) so a few years back fees were reduced for Y7-8. This is now attracting more and more parents that move their child there just for Y7-8, especially if the child was not successful on their Kent Test.
As a school they always had good grammar school acceptance rate overall.
Traffic can be an issue in and around Tunbridge Wells in general and especially around the school where the main road gets constantly gridlocked especially between 3.30-4pm as it's right next to a massive secondary (which by the way is an absolutely outstanding state secondary, just very big). That said, included in your fees are all lunch and after-school clubs so if you sign up for those, you can expect pickup at 5.15pm pretty much every day.
Most children typically continue to either TW/Tonbridge grammar school (like our daughter :) ) or a local independent secondary.