I couldn't quite get all updates included, but it's much easier then running WSUSOffline or Windows Update on every machine. Just watch out for KB2966826 & KB2966828 if you haven't enabled .NET Framework 3.5. If these are added without .NET Framework 3.5 being enable, it's hard (impossible??) to add later...
I have been using a mixture of WUD, WSUSOffline and running Windows Update on the completed ISO to get the updates, but always had a few left to do. I would be interested to now how you get on...