I'm here now and, frankly, I'm a little disappointed. There's what I think is a good review on Tripadvisor by 'ChristineH', she sums things up pretty well.

The staff are pleasant and well trained, even the basic rooms are a reasonable size, certainly by Tokyo standards, but the space is poorly used. There's a severe lack of flat surfaces and only one chair that falls between comfort and practicality and manages neither well. Bed is comfortable and shower good too. Relatively few power points and they're all Japanese style so bring an adaptor, there are also a couple of USB charging points.

The lounge is small, perhaps seating for 15 or 20 at most but I'd imagine that it would be rather noisy and feel quite claustrophobic with half that number. Small offering of evening canapés (4) and a little cheese but nothing much more available to eat. A red, white and sparkling wine - the pinot noir was ok-ish, plus a range of spirits, soft drinks, a sake and local beer (I think it's Kirin), plus tea and coffee. Not sure what the offering at breakfast is as I had mine in the main restaurant, quality and range of offerings there is quite good.

Welcome gift was underwhelming - a few madeleines and a couple of other sponge bites plus a small bottle of still mineral water. Welcome drink options are limited - same range of wines as in the lounge, a few Japanese beers and some soft drinks - hardly anything of 'my choice' despite what it may say on the card.

Location is a bit quiet but you've got the yamanote line on your doorstep so getting places isn't a problem.

At at the moment it's new and has that going for it, not sure it willl prosper though. A lot of competition at the price it's charging and I don't see that it's got a particular advantage to set itself apart from the crowd. I thought the lounge and other platinum benefits might do it for me, but I think I'll still look around to see what's available next time I'm in town.