Amy's lower unit was perfect for our week-long stay in West Seattle. The home itself is very comfortable. The location is also great, both for very short walks to excellent coffee (Youngstown, C&P) and food (HeartBeet Cafe), as well as a reasonable and beautiful walk to the Junction district, the coast, and the north end of Lincoln Park.
I noticed some people mentioning in their reviews sound traveling from the upper unit, but I didn't feel it was much different than what I'm used to back home at my apartment, mostly just hearing occasional footsteps. It was never bothersome or prevented us from getting sleep.
Overall, I would highly recommend and will plan to stay here again the next time we visit!