I stayed here last week. They stay itself was pleasant enough. I'm a total noob at Hilton properties and London. The building is kind of old, and it shows particularly badly in the carpet. The desk and chair were in pretty rough shape. The bathroom had clearly been remodeled, but not the rest of the room. I thought the shower not having a door was kind of strange. It took me a while to figure out that you have to put your key in the slot before you can turn any of the lights on.
Just on the basis of room quality, I'd find somewhere else next time.
My biggest complaint is that I was charged in dollars instead of pounds at an unfavorable exchange rate and with an extra 3.5% fee tacked on, to the tune of nearly an extra $200. Of course they refuse to budge and after reading other
people's experiences, I'm not going to bother trying to get them to refund it and try again in pounds and probably won't stay in a DoubleTree property in another country again.
EDIT: To DoubleTree's credit, somebody did reach out after I complained about this on their survey and offered to refund the conversion fee. Another win for passive-aggressiveness.