It has fantastic location and fantastic, friendly and extremely helpful staff. Few things in the room could be improved: bathroom door wasn't closing (it was catching on the frame), there was mould on a wall by the ceiling in a corner and water on a wall (poor ventilation in old British buildings isn't unusual, but since it's XXI century, it could be improved) and bath was in a rather poor condition (someone treated it badly during previous visits as it had visible cracks that didn't look nice). Private patio, kitchenette with kitchenware was great, though no place for the plates to dry after washing up. Great place to stay for sightseeing etc, as it has great public transport connections and if you have time you can easily walk to pretty much every place in central London.
There are things to improve, but it's definitely place worth staying and I will definitely consider it in a future.