We stayed one night and the bed was comfortable. The bathroom is just across from the room and is pretty spacious. Guests do not have access to the living room or kitchen (this was in the description so shouldn't be a surprise. Still not the common practice for private rooms listed). An electric kettle was provide to make hot water.
The view of London is nice. The railway tracks are very close so if you are sensitive to sound, it's best to keep the windows closed.
The buses are right outside of the door while the underground/tube station is almost a mile away. The flat is NOT at Elephant and Castle - it's over 1 mile away and is not the closest tube station.
Overall a good value if you have the right expectations.