I stayed at Celestine Hotel for a business trip in September. The staff there were extremely polite and helpful. I was also very impressed by the food and services for breakfast in the restaurant. There were great selections for both traditional Japanese and western style breakfast. Free high-speed WiFi access was another bonus. The room was very clean and comfortable. Overall, it was a very pleasant stay for a business trip. Highly recommended for a business trip in Tokyo.

I typically stay at higher class hotels in Tokyo, but had to get here for city overbooking. THe Celestine is not the fanciest hotel, Pool and Gym are absent, but rooms lack nothing compared to those I go to in 5 stars hotels (especially amenities). There's a fine lounge and personell is kind, with good, very good English (also the cleaning team, I found out).
The GrandRock restaurant deserves a special mention. Nice architecture, some less fancy details, but the chef displays excellent european selection. It's not the busiest in town, probably, but this restaurant deserves high ranking for food, dressings and service. I rarely am surprised by what is offered, but here I had two fully regenerating dinners.
To sum up: not the fanciest, but a safe, decent well located option.

Celestine is a top 4* hotel (don't expect 5* facilities). I was positively impressed as I ended up there- sceptical - during the busy IMF week and our usual corporate hotels were full.
Good location, Nice lobby, friendly staff, nice well equipped room with decent size for Tokyo standards. The bed was comfy, the view through the big windows very nice. I had north east facing and could see the Tokyo tower.
There is free wifi across.

Highlight: there is special filter coffee package available something I haven't see elsewhere.

Only downside? There are not linked with any frequent flyer programm.

I did not try breakfast.

My husband and I stayed at Celestine Hotel for 4 nights while we were in Tokyo. The hotel is a short walk from Toei Shibakoen Station, as well as Mita Station (exit A10 / A8) which has both Mita Line and Asakusa Line. Hotel staff spoke reasonable English, and were all very helpful. Their breakfast buffet was excellent both in terms of quality and choices!!!

To save some transportation costs, my husband and I bought the 1-way Airport Limousine tickets with Tokyo Metro 1-day Passes (promotional price, about 400-600 yen off the full price). The Airport Limousine dropped us off very conveniently in front of the hotel. (The Airport Limousine tickets alone is 3,000 yen per person, but if you throw in the Tokyo Metro Pass, and but them as a set, it only cost you 3,100 yen per person. There might be a minimum purchase of 2 sets, though.)