This was my second hotel in Tokyo. This hotel is great in every way.
I had a room on 34th floor. I had a great sightseeing of tokyo.
The room had everything even a Personal computer with internet.
I you want to stay in a really good hotel in tokyo than choose this one
or Tokyo park hotel wich is about 30 meters away from this one.

I stayed there for 3 nights in Feb 08. The airport bus to the hotel did not run so frequently, therefore took the Narita Express train to Tokyo Station, then a short taxi ride to the hotel.
Hotel Lobby, restaurant and room were nice. It was a very good business hotel rather than a luxrious hotel. I like the corridor that leading to my room. Room and bathroom were in good size (Japanese standard). Unfortunately the window of my room was facing an office building and one could not open the window blind for any privacy. There was a computer in the room via the television. However, the cable socket for my own laptop was not working and therefore needed to use the computer cable for the TV instead. There was a safe in one of the drawers but that drawer kept sliding opened. Light could be a little brighter in the bathroom.
Breakfast at the western restaurant was pretty nice with good view.
Overall I enjoyed my stay there.

We stayed at the shiodome for 8 nights, the hotels services were FANTASTIC.. the internet in each room is what sold me, i loved being able to see the weather each day and plan our day trips inside the comfort of your own room. Even when we had a problem with the TV, they were quick to react and fixed our problem.
The Shiodome is located in the heart of business Tokyo and walking distance to Ginza, so not too many tourists around here, just ppl travelling to Tokyo on business. The tour companies use it as a pick up hotel, so that has advantedges. However if you want the more Tokyo buzz i suggest staying over in Shibuya, Harajuku or Ropongi.
Another positive is that JR Shimbashi station (for those with JR rail pass), on the main Tokyo loop line is a short walk from the hotel, for non rail pass uses, the Shiodome station is close by, so you can get around easily. Additionally the monorail to Tokyo Bay (Odaiba) is also walking distance.
The negative side to this hotel was the guest services staff, we found that if you weren't dressed in a suit, then they will ignore you to a level of rudeness (ie. prented to make phone calls until you go away) We asked them to see if they could book a tour for us, after saying yes, they never did, and we did it ourselves with our broken Japanese.
The hotel has washing machines and dryers for use, if you do not wish to use laundry services, very handy for those staying some time in Japan.
For the price, I would recommend other hotels than the Shiodome. I only stayed here as I was able to obtain a corporate discount.
BTW, we booked a semi double room, it was more than comfortable for 2 ppl and the bathroom size was decent. I would recommend, to save some Yen, go with the semi double.

While no longer 'new', I have been staying at the Royal Park Shiodome Tower for my annual visits to Tokyo since the hotel opened. It may not be the fanciest or the most glamorous, it's nevertheless a really reliable hotel that never lets me down. The location in Shiodome/Shimbashi is most convenient with easy access to a number of key subway lines, JR and otherwise. It's walking distance to Ginza, but for me, the highlight is its proximity to the Tsukiji Fish Market. If you're up by 5 am with jet lag, just walk over to the Fish Market, just at the right time when the tuna trade heats up. The whole "Shio Site" (as the locale is called) is a complex of office buildings (Dentsu, Shiseido and ANA have their HQs here), creating a very futuristic "Blade Runner" like environment that's spectacular especially at night. Every room at the hotel has a great window and the view is fantastic - big sky with hawks during the day, and sea of buildings and blinking lights at night. The complex is also packed with both retail stores and restaurants, making it very easy to either eat in your room with store-bought foods or eat out. And typical of Tokyo, even after dark, it's absolutely safe to wonder around the complex. The hotel is reasonably priced, and even though the rooms ARE on the smaller side, it more than makes up for the lack of space with everything else. It also has a small but very accessible gym (it's hard to run outside in this neighbourhood), and even a coin laundry room (convenient for a quick wash). When you book, make sure to secure reservation that includes free breakfast coupons. While I prefer to eat breakfast at Tsukiji (excellent bowl of tuna over rice plus miso soup can be had for less than $10), the hotel has a very nice Japanese restaurant that serves Japanese breakfast, as well as a bright western buffet-style breakfast place that has great views. The staff is mostly Japanese, but are most helpful.