As several other reviewers have stated, if you are going to book a reward stay with Hilton Honors points, this is the place to do it. Further, if you are Hilton Honors Gold or Diamond member, you also can receive free breakfast vouchers, making a very good deal an even better deal.
We stayed five nights at the Conrad Tokyo on Honors points, were upgraded to a garden / bay / ocean view room and given breakfast vouchers. This is a much better way to use Honors points than 20,000 a night for a suburban Hampton Inn!
The hotel is fantastic. The service was impeccable. The 28th floor lobby is a bit overwhelming in terms of scale and the views over the bay to Odaiba and the Rainbow Bridge. The rooms are very spacious, and high tech. In fact, for the same points per night as the Hilton Tokyo, my read of the two hotels' web sites is that the Conrad rooms are 60% larger. The rooms feature floor to ceiling windows with electronically operated blinds and curtains. The bathroom is spacious as well, with a separate walk in shower and toilet stall. That way, you can keep the blind between the bathroom and room open and still have privacy. Of course, that blind opens electronically as well!
The breakfast area is very well laid out - there is much more to it than you will see while walking from the lobby to the elevator bank. There is a very good breakfast buffet and hot breakfasts are 850 yen more than the buffet (the vouchers pay for the buffet value only).
We were very pleased with the hotel service as well. They were helpful in making our return airport "limousine" bus reservations, in making dinner reservations and directing us to various stores in the surrounding area.
About the only niggling complaints I would have about the hotel are two. First, there is a very nice reading light by the window sofa, but we could not figure out how to turn out other "room" lights and leave only that on - which would have been a great option when one of us could not sleep due to jet lag. The second is that to call AT&T USA Direct, I had to go through a hotel operator at a rate of 36 yen per minute. We probably could have bought a cheaper prepaid phone card on a Japanese network, but did not bother for the little use we had for making international calls. If you were traveling on business, this would be something to consider.
The hotel is well situated. The Hama-rikyu gardens are across the street. The Tsukiji fish market would appear to be within walking distance (although we did not go there - at any rate it is one subway stop away on the Oedo line). The Ginza strip on Chuo Dori is about a 15 minute walk. The hotel is well situated for public transport as well. The Oedo line is outside the front door, down an escalator (with motion sensors and voice warnings to hold the hand rail!) and then about a 100 foot walk to the station entrance. The Yurikamome line to Odaiba is out the front door, up an escalator and immediately on your left. There are above ground and underground pedestrian walkways to the JR Shimbashi station, which also has subway stops on the Asakusa and Ginza lines. From the JR Shimbashi station, one can board the loop Yamanote line. Shimbashi is two stops south of Tokyo station, terminus for various Shinkansen (aka bullet train) lines. Oddly, while one can walk above ground and below ground, one cannot walk at ground level - there is no pedestrian crosswalk at the corner of the hotel!
If you don't want to eat at the hotel, there are plenty of restaurants of all cuisine varieties and price ranges within walking distance, including several on the 41st and 42nd floors of the Shiodome City Center building, with excellent views. We particularly enjoyed the Vie de France in the basement of the Shiodome City Center building.
There is a Seven Bank with an ATM that takes US ATM network cards on the 1st basement level of the Caretta Shiodome building as well. By the way, for a helpful map of the Shiodome area for your first day or two in the area, check the Caretta Shiodome web site for a downloadable pdf english map. However, the area is well signposted in both japanese and english.
Overall - great hotel, great amenities, great service and a very convenient location.