We stayed at William's house for two nights and it was exactly what we were looking for. The house is in a gated and quiet area, with parking space available and about a 10-15 min walk to the city center.
The room was clean and quiet, with a private bathroom and great shower, although you can't take a shower between 11pm and 7am, in order to avoid waking other guests.
William is a great host, communication was always immediate and clear. The day of our arrival we got in a bit late and he waited for us to check us in. He explained everything about the house and even gave us some tips.
There's a light breakfast available (bread, fruit, yoghurt, oatmeal & cereal), just enough to get your day started. Although you can't properly cook, you can use the kitchen basics; fridge, microwave, toaster, etc.
Great place to stay if you need a home base while you explore Killarney and it's surroundings.