I agree with previous posts about the room design and Platinum upgrades. Just finished a stay there -- I booked it because it was new and got a good rate, but read this thread after and almost cancelled. I should have. I have stayed at many Ws, and this one is probably the worst I've stayed at with respect to room design. The rooms are small, even for London, having the bathroom sink in the middle of the room is inconvenient (and allows them to make the bathroom area even smaller), and the lights are impossibly difficult to figure out. If you want to turn all of them off, you need to use one switch marked with two circles, and concurrently press a completely unmarked switch next to it, then hold both for several seconds. How any normal person is expected to figure this out is beyond me. It took a few minutes of explanation on the phone and I'd be willing to be they have this conversation many times a day.

My Platinum upgrade was minimal (higher floor room) despite the hotel having rooms in most categories available, and the rooms were not ready when we arrived at 6:40pm.

I would not stay here again. SPG has a bunch of bad options in London, but this is pretty near the bottom of the list for me. Both LM Piccadilly and Sheraton Park Tower are much better, IMHO.