The FS Chinzan-so exists mainly off of wedding business these days. It really can't be recommended for a tourist because of the horrible location. That 10 minute walk someone mentioned to the nearest subway line is 10 minutes because it is down a steep hill -- which you will have to walk UP when going back to the hotel.

However, because of the location, you can sometimes get amazing corporate rates, if eligible, and if you are on a lower budget and must have FS, this would be where you end up.

Really, there is no choice. If you're a FS-all-the-way person, it's FS Maronouchi for you.