Otera Stay comprises two self contained studio units. Both are very large by Tokyo standards, clean, modern and tastefully furnished. They connect seamlessly so if you have both (as we did) it works well as a two room, two bathroom space. We had kids and grandma sleeping downstairs, and parents upstairs with a later bedtime. Note there is no privacy within each studio (ie wouldn't work well for two couples because the beds are immediately next to each other). Also, there is no door between the sleeping and living/eating area within each studio. However, the two studios can easily be isolated from each other.
The area is convenient and quiet. It has great local eateries two blocks away (in the direction away from the train line).
The one big negative for us was the very busy train line which is very close. Even with the windows closed and A/C on, we found it quite loud and nearly continuous. If you are used to city noise this won't bother you, and it does stop from 1 to 5am.