I stayed at the start and the end of a trip to the Kalahari. Hennie, who runs the place was a wonderful hostess, the room was comfortable and clean, and the views from the end of the garden were stunning - I could have spent weeks just gazing across the Orange River watching the many birds that make the place their home. Breakfasts were fantastic - they set me up for the day, and were varied. Hennie's dogs were also wonderful (if you like that sort of thing!) - well behaved, but affectionate, adding to the feeling that this is a home away from home.
My only potential concern as a single woman was walking home after going out for dinner - the guest house is down a back street - I never had any bother, but it might be something that would concern other travellers in my situation - however, Upington seems to be a safe town and I never had any hassle.