We booked this reservation for 2 in the end of April for 10 days.
This was our first trip to Tokyo so we were kind of afraid of how this was going to work out but both hosts replied to my concerns and questions very reactivily.
The self check-in/check-out is a real plus, you're free to check-in whenever you want as long as you can store your bagages in a coin locker in some station while waiting for the host to finish preparing the room.
The self check-out was also perfect to leave very early in the morning to get the first train at 5a.m and get back to the airport without bothering the hosts with such an early appointment.
The appartment itself is pretty huge for the price, you really won't find something as cheap for that kind of place anywhere else in Tokyo. On the otherhand, the price to pay is being far from all of the real "active" districts of Tokyo. Besides Asakusa which is about 15min to the appartment, most trips (to Shinjuku for example) take around 45 to 60min, so be careful of the last train if you plan on spending the evening in an izakaya and karaoke like we sometimes did ;) Also beware, you will probably charge your PASMO/SUICA more than you initially planned because of this.
There's everything you can think of in the appartment, so no use bringing your own towels and stuff. The wi-fi is extremely convenient and has pretty decent autonomy, it can last up to a whole day, but you might want to bring an external battery just in case the battery dies when you plan on getting home.
As for the location itself, the appartment is conveniently placed, there are at least 2 combinis nearby, and the station is at less than 5min on foot.
The one thing I might warn you about though, is that since it is a residential area, the stores and restaurants tend to not be used to have tourists, so speaking a tiny bit of Japanese will help you a great deal if you want to eat nearby.
I'll definitely try to book one of Masaki's appartment next time I visit Tokyo, thank you very much!