We paid extra for a superior room with two beds which according to the description at hotels.com should be 16 m2. The reason was that wanted to have some more space and that we thought that a room with only 12 or 14 m2, the smaller room sizes they had at the hotel, would be too small.
When we came, we were given a room in the basement with no windows. The room was so small that there was absolutely nothing but two small beds in it (maximum 80 cm wide). Hardly any floor space on any side of the beds - 30-50 cm between the beds and each of the walls and in between the two beds. You could literally do nothing in there but enter the room and lie down on the beds. The room was definitely not 16 m2, I would be very surprised if it was even 12 m2. My estimate is that it was 8 or maximum 10 m2 (including the bath room).
When we complained about the room, they said the hotel was full and that there was nothing they could do about it and that we had got the room we had paid for.
So be aware, when you book a superior room and pay extra for a larger room at this hotel, there is a risk that you will not get what you were promised in terms of room size and also a risk that you will be given a room in the basement with no windows at all. I don’t think that is what you should expect from a four star hotel.
In summary, we were very disappointed with the room and I do not think we were given “value for money” compared to other tourist hotels in London (been here multiple times).