We loved staying at Dots, it was a very unique and unusual place to stay. The staff at the front desk were lovely and it was in a great location.
Overall, it had the feel of staying in a caravan or tiny home.
The bathroom was excellent and spacious. Heating was great. The location was 15 minute walk to Ueno train station and very close to kitchenware street and Sensoji Temple (go there at night, it's so much better without the crowds!!!)
However, if you are tall, wide or can't manage awkward steps, this is NOT the place for you. The bed was on the floor (with only one pillow and no extra blankets), we were unable to stand up in near the bed. The mezzanine lounge area also had a very low roof, my husband (178 cm tall) was only just able to stand up in the the area, I would estimate the roof was 180cm high!!! It is impossible for two people to pass each other by the lifts, in the hallways or on the steps.
There were also limited views of Tokyo Tower from the 4th floor, I was a bit disappointed about this as I was really looking forward to seeing from our room.
BUT... if you want a really unique Tokyo experience, then this is definitely the place for you!!!