I stayd at the Rihga Royal Tokyo for three nights. My room was very nice, quite large and very clean. The beds were comfortable (not too soft) and the room was quiet.
Good breakfast, very nice and helpful staff. Hotel offers a free of charge shuttle bus to the next station where you can find a shopping center and many restaurants.

I loved this hotel. My room was large and gorgeous. There are many nice amenities in the room too. The bathroom is great. The only drawback was that the location of the hotel seemed a little out of the way, but it made for a very quiet stay. The staff is very cordial and eager to please.

Really beautiful, quiet hotel almost adjoining to Waseda University though the garden. Big well maintained rooms. We were upgraded to a junior suite, which boasts double vanity in the bathroom, 2 flat screen TVs, spacious seating and working areas and lovely view of the waseda university garden below.
But... if you are not familiar with Tokyo and its subway/bus system and don't at least understand Japanese, better stay some more business/touristy properties. The nearest metro station is 10 min walk and it's not easily connecting to others. The hotel provides a complimentary shuttle bus (runs every 30 min) to the nearest JR station, which takes about 10 minutes to get there and again it's only Yamanote line which is a round service, so some destinations may take over 30 minutes ride...
Don't be mislead - the hotel is not in Shinjiku, it takes 10 minutes shuttle ride to the JR stations and 2 stations by train to actual Shinjiku...

I just returned from Japan and one of the hotels I stayed at was the RIHGA Royal Hotel. I had some trepidation about booking here because one of the reviews stated how out of the way this hotel was. Will I was pleasantly surprised to find that there is a shuttle to a JR Line terminal and once there you can get anywhere. My business was at Sunshine City which I was able to get to taking a tram that is 3 blocks from the hotel.
The service was great and our large room overlooked the garden. The bath had a separate WC and the tub was one of the biggest I've seen in Tokyo. Breakfast was expensive so we headed out for our morning meal and we were never there for the other meals.
For a Tokyo hotel I think this is a place to stay at a good price and great service. I will stay here again if my trip puts me North of the Tokyo City Center.