tl;dr great place, great hosts!
We stayed at the Pine house for three nights on our arrival in Tokyo. The place is amazing! Two floors, with two bedrooms. One with beds and one Japanese style bedroom, which we used. The apartment is well taken care of and clean. Good internet and all facilities you need.
It's easy to reach by train from Narita airport. The apartment is close to the keisei-tateishi station, where you can catch a train into Tokyo every 10 minutes.
Best of all are the hosts Koji, Nami and Mr. T. They gave us advise on the trains, Tokyo sightseeing, brought us fresh apple juice and gave us a ride to the station when we left.
We stayed there with our 10 months old son. It's very well suited for kids/babies as they can sleep in the other bedroom. Also Nami came around every day to give the boy some extra cuddles;-)