Jennifer and David are friendly, responsive, and helpful hosts. The caboose is in a great location with easy access to Ballard, Fremont, and Green Lake. I felt very safe there. The bed is on the firm side and really comfortable. The showerhead has lovely massage setting and good water pressure. And there's a good coffee place within walking distance.
I'd recommend the caboose as a great place to stay for anyone except light sleepers. It is raised from the foundation and is near a major road. There's a little bit of traffic noise, which I blocked out easily with ear plugs and white noise from my phone. However, when heavy vehicles drive by, the entire floor (and, thus, bed) vibrates. Sometimes it's infrequent, other times it's every few minutes. I stayed long enough to get used to it, but it woke me up a lot the first week I was there. I think it's probably only noticeable to light sleepers, though—my husband didn't notice being woken up by it at all.