There are so many great things about this hotel that it's hard to know where to start. So here's a list...

The Good:
Fabulous views of the Tokyo skyline THE most comfy and enormous bed (we reckoned room for five, although we didn't test that theory!)
Great bathroom - shower, nice deep bath, double sinks, separate toilet complete with plenty of buttons (very Japanese) Great location near Shinagawa station which means you can get anywhere very easily (never took a taxi the whole time we were there) You can also use the facilities in the two adjoining hotels - Takanawa Prince and New Takanawa - including business rooms, breakfast, restaurants etc etc
Very friendly and helpful staff - nothing was too much trouble to sort
You get rewarded for being environmentally friendly - like big hotels these days, there's the usual request to reuse towels, which considering the number you're given is certainly no hardship. In return you get a voucher to spend in the hotel's shops/bars/restaurants - as I try to do that anyway, you get to feel virtuous and get rewarded. (Even if you opt for this, they change the linen on check-in/Check-out and every other day anyway, in case anyone is worried about cleanliness standards.)

The OK (certainly not bad though!)
Room service was good but not desperately cheap, but it's so easy to eat out it probably won't matter. Same goes for breakfast - fine but nothing to get wildly excited about (good coffee though)
The wine bar wasn't the most happening place - we checked partly for the novelty (made a change from sake and beer) - but as we were spending our vouchers (see above) it was a freebie anyway.

The bad:
Nothing. Honest. I genuinely can't think of anything I'd change. (Well, unless they could make it free - but compared to hotel prices in other big cities, like London, it's a bargain for what you get)