This apartment was great and literally a 2-3minute walk from the train station, and a big supermarket is just 1-min away. The apartment is a good size for Tokyo, and has pretty much everything you need, including a washing machine and dryer (dryer is built into the ventilation system of the bath/shower room - you will see if you come - very easy to use). The mobile internet unit is also very easy to use and I did not have problems with it at all.
Shimo-Kitazawa is a very convenient location to get around Tokyo if you want to stay in a less busier part of the city. Make no mistake, there is plenty to do (eat, shop, drink, hang-out - including live music) in Shimo-Kita. It is a trendy area, but it's not crazy busy like Shibuya or Shinjuku. Yet, it's just a short train ride to both those locations (take the express train and it's one-stop, as I recall). I think this is important if you are new to Tokyo, and you have to drag your luggage around - so you don't want to stay in a busy place like Shibuya or Shinjuku (huge crowds, big streets, giant train stations - tough if you are new and have luggage).
Daisuke's place is also reasonably quiet at night and the neighbourhood has plenty of cafes as well. And Daisuke is very helpful and a great host. I am very satisfied with my stay and will choose his place again when I visit Tokyo next time.