This room was a great place to stay for a week in Shinagawa; it had pretty much everything we needed and was well laid out (enough room to feel spacious, the most useful amenities like a combo microwave/oven and washer, etc). The primary downside is it's a fair walk from the nearest train station; a beautiful walk, mind you, but still a good 15-20 minutes. However, once you're there, the nearest kombini is a literal minute walk away, which is quite useful.
The only problem we encountered was that the previous tenant had lost the A/C controller -- but the owner quickly resolved this by overnight-shipping a new one, leaving us with less than a single day without it. Additionally, the owner was able to receive takkyubin luggage for us even before we actually moved into the place, which was really useful and convenient.
Would definitely recommend if you're okay with a bit of extra walking.