This Starbucks is located outside the ticket gates at the new Takanawa Gateway station on the Yamanote line. There isn't much around since the station, which is part of a large redevelopment project in the surrounding area. The station features a nice design with plenty of natural light. The Starbucks is located on the balcony above, overlooking the station.
To access the Starbucks, take a right just after exiting the ticket gates. Follow the "coffee cup" sign which leads you up a set of stairs.
The Starbucks features their "Smart Lounge" concept. There are two zones, one just as you walk in, and another to the left of the ordering queue. The left side was very quiet, and features several partly enclosed booths. Personally I like the counter seats, overlooking the station.
The WiFi was very fast, and most (if not all) seats have individual power outlets and USB charging ports, which was great! Seats aren't the most comfortable though, but it's fine for maybe an hour or two. Early morning was surprisingly busy, mostly business workers coming in for a coffee before work I guess. Late morning before noon was fairly empty.
There are actually two "STATION WORK" booths in the back as well. Pro-tip: if you connect to the STATIONWORK WiFi network you won't have to constantly reconnect, like with the regular Starbucks WiFi.