We are a family of 3 and we stayed comfortably at this apartment. It is a 2 bedroom apartment that was quite generously sized for Tokyo standards. I've been told that apartments in Tokyo are shoe box sizes due to the limited space and density of the city but this was spacious to my surprise.
There is a noodle shop on the first floor of the apartment which is open till very late and also convenience stores near by to grab your breakfast on the go when you are ready to explore the city.
There are a few eateries around the apartment in case you don't feel like traveling too shinjuku or shibuya. I recommend the noodle shop and Okonomiyaki place (Japanese pancakes but note it's not sweet!) around Sangubashi Station.
Transportation wise the closest station is a sangubashi Station on the Odakyu Odawara Line that connects to Shinjuku directly as well as Shimokitazawa, it's known for vintage things and used clothing, there are little joints that you can just walk...