The apartment is walking distance to Keio New line subway station in which you can hop on to go to Shinjuku station. If you are planning to go visit the tourists attractions such as Akihabara, Harajuku, Asakusa and etc, you will need to transfer twice when using train.
It is true as with the other comments that you hear the traffic noise inside, so earplugs will come in handy. The space is quite adequate for 2 people but not much wiggle room if you have both luggages open on the floor. Is it described as bright and cosy and these are true. If you like to sleep in a dark room, this might not suit you as lights from the highway come through the curtains however eye mask can somehow solve this. Overall its a good place to stay in.