Sarah and Gael's apartment was the perfect base for our eight days stay in London. The location was super convenient, only 10 minutes walk from Kings Cross/ St Pancras International . The station has direct trains from Gatwick Airport as well, so no need to hassle with transfers. Kings Cross station was also connected to many lines with the underground, so it was perfect all around for exploring.
As other people have mentioned, the apartment is indeed loud in the lounge room as it was in the front facing the street. However, it is quiet with the doors closed while in the bedroom at the back (still some excessively loud cars and people can be heard but it wasn't that bad).
Photos of the apartment itself are accurate. Would only recommend two people max to stay due to the sound from the front. Kitchen is small but we mainly ate out or had reheated leftovers. Fridge needs to be turned to the '7' setting while on, otherwise the temperature is not cold enough. The hot water kettle also has some built up scale inside it so we didn't use it much (hopefully the hosts can provide a new one!). The apartment was also warm enough during February, we didn't know how the heating system worked so left it as is.
That is probably everything future guests need to be aware of. Communication with the hosts went lovely but keep in mind that they operate with automated messages most of the time (followed by a more human response shortly). So, something to keep in mind :)