We spent 2 nights with the grandchildren, 11, 8 and 3. There was lots of room and the place was comfy. The kitchen had everything you need, and there was a little laundry room though we didn't need it.
The grounds are great for kids, there are lots of outdoor toys and space for them to run around in. Caernarfon is about 10 minutes away by car and there are plenty of activities in a short radius, including beaches.
The owners are helpful and friendly, the only issue was the weather but that is not anyone's fault.
Overall a great place for a few days with kids.