Ohkubo is a very good host. He provides very detailed instructions to find the appartement and to use the different equipment.
The appartement is located 5 minutes from the nearest train station (Yamanote line). Shinjuku (big train hub) is one train station away or at a 15 minutes walk, so you can access pretty easily all different Tokyo's points of interest from the appartment.
The street is really quiet and close to many restaurants, convenient stores or bars.
The appartement is clean, very well equiped and as described.
I strongly recommend Ohkubo's place.