Architecture fans will love this place. The owners have taken a brutalist office building and turned it into a super-cool hotel. Attention to design details is impressive, the fundamental character of the building has been not just retained but put firmly center stage. It's also in a great location directly opposite St Pancras station.
That said . . .I had a king room, which had great space but an awkward layout. The bed is literally in the middle (so you can walk all around it), there is an oversized alcove eating space (why so much table space for two people?), but no obvious place to keep your suitcase (wherever you open up the stand provided, your suitcase will be in the way). There is a good size desk but it serves as the headboard, so it's quite tall and therefore has a stool rather than a chair.
My main concern is the apparently total lack of interest in sustainability. The room only has two small bins, and none for recycling. The default position is to change linens every day (you can leave a card to tell the cleaner *not* to change the bed), and the usual rule about towels (hang up to keep, on the floor to replace) is not used here, so towels were replaced every day. The toiletries provided were all made in China, when in fact for a high end hotel like this, UK-made products should be the standard. The restaurant menu did not appear to refer to organic options, or sources.
Overall, you pay for a super cool ambiance, but not true luxe like a grand hotel.