Ok, think I have this one worked out, not seamless by any stretch of the imagination, but here goes.
Create your document, be it keynote, pages or numbers, do not share it to iWork via the menu within the application, note I said DO NOT.
Open a browser window and logon onto www.icloud.com using your apple ID. You will see various applications including an icon for iWork, click this.
You are now presented with a window with your created documents on your IOS device if you have any, you will see a bar at the top of the page that lets you go between keynote, page and numbers.
At the top right it the apple cog normally used for system preferences in IOS applications, click this and you will be given an option to upload document, click this and you are given a search window to browse your Mac, browse to file and select the upload option.
Open you IOS device and then run the relevant application and note that the file is now there.
You should also be able to open any files on your Mac created in an IOS device by doing highlighting the relevant file in the iWork portion of iCloud and selecting the cog again and choosing download document, you are give 3 options for a pages file, pages, word and pdf (i have not checked the others yet), select the one you want, I selected pages and the file downloaded and opened on Pages on my Mac. Make any changes that you want and upload the file again, it then prompts you to replace the file on the IOS device.
I have done this and it has the document sitting in the iWorks folder in the iCloud.
I hope this helps a few folk out there in Apple Land and maybe, just maybe reinstates a little confidence in what Steve Jobs was trying to do. It might not be seamless, but if you follow the instructions, guess what "it just works"