Really, I have NO idea what some people complain about in in some of the reviews below! I and my husband stayed for a week here and couldn't find even a single thing to fault.
We took the airport limo bus from Narita to Conrad's door step. The lobby is in the ground floor, you need to take a lift to the reception in 28th floor, and from there another lift to your rooms. Check in lasted less than a minute. Ours was a super-spacious King suite with city view. The bed was super comfy, and two huge TVs, one in the bedroom and one in the living room, both rooms had city view of the river and the high rise buildings.
Service was very efficient and unobtrusive. Every day, after hectic sightseeing, it was bliss to return to an impeccably made room. The staff were available any time to answer our queries.
Reg food - The buffet breakfast, which was awesome, was served at China Blue restaurant. My husband found it a bit repetitive, but I didn't - the fruit / cornflake / bread / cold cuts / porridge / cheese / pudding stations were extensive, and the egg menu had 9 different options which offer variety. The food itself was very tasty, obviously, being made in a 5 star hotel!
Yes, the location is not fantastic, but that's hardly the hotel's fault! Minato is generally not the right place to stay, if one needs to be central.... To be near tourist sites, better to stay near Shinjuku or Shibuya. We knew Conrad was a business hotel, so we were prepared to tackle the transport connections (a metro map is a MUST, if you don't want to spend a fortune on taxis). From Conrad, we enjoyed daily metro rides from the Shimbashi metro station (15 min walk underground, starting from the Shiodome City center basement, located under Conrad).
The Shiodome city center has some reasonably priced, good restaurants (we had some dinners there). You can also walk, on the connecting bridge, to Ginza (10 min).
All in all, highly recommended!