I only had one night in The French Guest House when I arrived in Jo'Burg airport. Laurent picked us up from the airport. He gave us advices to visit the city. we called a Taxi, because it's quite far.
The room we had (triple) was clean, with private bathroom, enough confort for one night.
It's a good B&B if you want to stay close to the airport, but if you want to spend more than a couple of nights in Johanesburg, I would recommend a B&B closer to the City center.