Good location, clean and spacious for our family of 4 including a 6- and 15-year old. They were fine with the narrow spiral staircase (which goes down from the kitchen/eating area) but I would be nervous with any younger (or more stumble-prone) kids, or any older/other people with mobility issues, though there was a gate that could be closed at the top of it.
It was hot the first days we were in Seattle so everyone wanted to spend most of their time in the basement! There were good instructions on making best use of the fans in each room. Kids loved the big couch downstairs. Overall it was a good base for our 4 days of exploring Seattle. Those with kids should check out the neighborhood especially Archie McPhee's down the street!