The ZZ House location is a reasonable five minute walk to the Iron Bridge and a twenty minute walk to the old walled portion of Chiang Mai. Note that there are no sidewalks for a large portion of the walk, so be aware of traffic (mostly one way). The street is quiet, although there is a school across the street where there was a band conducting practice out in the courtyard at ~9:00 AM (not sure how common that is though).
The thing that makes this guest house amazing is the young man who runs the place, Boyd. He appears to do everything and has great English skills. He is also nice and giving to a fault. He will personally greet everyone, providing insight and ideas. For Loi Krathong, he personally escorted a group of ~25 of us to the temple and then to the river side, coordinating with locals to have pre-provided candles to set out on the river and lanterns to release into the sky. We then returned to the guest house to let off fireworks. At no point was money requested, so as far as I could tell, he likely paid for most people out of pocket (I paid him when I checked out, but not everyone in the group was still lodging at the guest house). When I needed to go to the airport he fetched a tuk tuk to pick me up, getting me a rate MUCH lower than I would have expected. Overall, the location is good (not great), but having Boyd available made the otherwise great experience of being in Chiang Mai phenomenal. I absolutely would recommend ZZ House to others.