Great position
Stayed for 5 nights in Hotel Nikko, upgraded to deluxe room which was fantastic, two queen sized beds. Comfortable beds and lovely linen, nice decor. Bathroom was spacious, very clean. The pool on the 5th floor was a pleasant temperature, although the shallow end being only 2'6 made it not really suitable for serious swimming. The jacuzzi was extreemly hot, on the point of being unbearable! Sauna and steam room were fine.Didn't use the gym but it looked as if you could have a fair workout there, all the usual equipment.
Reception staff were efficient, friendly and helpful. As we did not have breakfast included in our rate the Starbucks adjacent to the hotel was ideal for the days we did not want a arterty clogging full american breakfast! And free wi-fi in Starbucks.
The position of this hotel was ideal, no more than 5 minutes walk to Union Square, but not noisy at night. I would not hesitate to recommend this hotel.