I stayed at Ko's place with my husband and 2 toddlers for about a week. We really enjoyed our stay there. We particularly enjoyed the spacious feel of the apartment as this is a rarity in Tokyo. Ko was very nice. He greeted us at check in, helped us carry our luggage up and gave us a list of restaurant and shop recommendations. He spoke English very well and was very helpful with queries and prompt with replies.
The convenience of the station being a minute's walk away was also great! As noted by other guests, you can hear the trains from the apartment but it didn't bother us too much. The apartment was also well decorated. It is on the third floor of a building with no lift so it may be hard for less abled travellers or travellers with young children. Our son however, enjoyed climbing the three flights of stairs. It is located a little further out from all the regular tourist areas such as Shinjuku and Ueno but there is a rapid train that will get you to Shinjuku in about 12 minutes and Tokyo station about 28 minutes. It's worth noting that the rapid service doesn't operate on weekends.
There are plenty of restaurants within a 5 minute walk from the apartment, there's a 7eleven practically next door and a massive supermarket called Seiyu. The entrance is abit inconspicuous but it is next to the flower shop.
All in all, we had a great stay at tasu toco and would recommend it if you're looking for an apartment with a bit more space or with convenience to restaurants, shops and the train station.
Thanks again Ko!