Stayed for a week for a conference. Arrived on the Limo Bus from Narita AP at around 11:30. Was told we'd have to wait until 15:00 to get into the room. On the same subject, while the checkout time was quite late (12 noon) the option of a later checkout was going to cost us Y80k. This was a lasting impression of this hotel. Lovely but inflexible and not very generous.
However this was a lot to like about the hotel. Great location for access to the academic precinct (Miraikan et al). Away from the insane waves of humanity you get in Tokyo proper. The robo-train line (Yukikamome) is awesome - cheap, quick and reliable.
Room had a great view out over the port (harbour). Good quality room fitout. Firm bordering on hard (by Western standards) mattress. Bathroom was nice. Bidet toilet (if you haven't used one before it's quite an experience!) Plenty of power outlets. Mini-bar and 'smart' hot water boiler. Given how tight the hotel was being in other respects I was bracing myself for an extortionate Internet access charge - but was pleasantly surprised Y10k for the whole stay. Quick too. I have my own wireless travel router so the standard wired connection was fine.
Staff were very friendly and welcoming.
Breakfast buffet had a great range of Eastern and Western options. Be early or you'll have to wait (although the turnover is quick). We ate at the Icho teppan bar restaurant. Horrendously expensive but extremely good!
If you want to eat a bit cheaper some nights then the food court in the bottom of the mall opposite has some good cheap options (the Korean is good).
I suspect the close cost control is due to the type of operation. These big flash hotels have a *lot* of staff. Just in the lobby there were >5 behind the front desk plus 3 floor walkers plus porters etc etc. Pity they couldn't relax things just a shade re things like early check in. Would have been 5 stars had that been the case.