Yea, Kremlin could be the best defensive wonder out there. After they nerf AW healing generals like crazy, definitely. The problem with it is that attacking wonders are also good in this age ))) actually, I can survive without air buff and factory is kinda useless, but if they buff it on build times it could be a whole new story.
Nice post Jwinn, which tells that if you're gonna build around Kremlin clean the land in square. fc may be better with longer build zone.
Also, it's good to know it buffs gates too.
Its second power with farm defenders is good vs raiders I think this layout is not using it.
May be it's still better to put double walls on one side and try Kremlin covering the remaining 3, so it does not waste space inside, tho