Although Marion was not available to hand us her keys, she sent very good instructions and phone numbers for herself and also her neighbour who very kindly helped us find the apartment by meeting us at an easier to find spot about two minutes from the apartment. If we had looked at a map before arriving, it really woul have been easy to find. There are a lot of places to eat and drink near the apartment, as well as a Spar.
The Capucins area is only about a 15 minute (slow) walk to the main part of the city centre (e.g. around the Place de la Bourse and Grand Theatre) along a pedestrianised strip which feels very safe. There are a lot of shops and MORE places to eat along here.
Although at first I wasn't sure about the Capucins area, we later spoke to some bar staff who wanted to live there and they explained that it's an area where a lot of (for example) Parisians are buying property because the area still has character. When I asked about safety they said that they thought it was absolutely fine, which is reassuring.
The apartment is very simple, clean and convenient. There were two of us staying and for just a few nights it was completely adequate for our needs. Marion left us everything we needed including a map of the city and her WiFi code - there was nothing more we could have asked for, but Marion had said to phone her if there were any problems.
My only caution would be for women travelling alone and is not intended to put you off but more for information: consider what time you will arrive in Bordeaux as the area around the train station and the road we walked up from the train station is probably unpleasant at night as it wasn't great in the late afternoon/evening (like many European train station areas). But once you're up in the Capucins area I think you will be fine.
Overall, I would stay in this apartment again - there are no real negative points to mention, and to summarise the positive - clean apartment, helpful host, good location.