This page has greatly been updated, see here:
The Windows Media Creation Tool is far superior to the previous Windows 8 and Windows 8.1 Downloaders.
It allows download of a .iso with selection of language, architecture and edition. Importantly it allows download without input of a product key. This means it can be used both with OEM product keys and RETAIL product keys and no "unofficial workarounds" are required. The "We Can't Connect at the Moment" error as a consequence which previously meant the key had been used too many times is a thing of the past.
The Windows 8.1 "Edition" with Update 1 .iso accepts both Windows 8 "Edition" and Windows 8.1 "Edition" product keys both OEM and RETAIL so theres no need for the use of generic product keys for installation, RWEverything to determine the OEM key and change key for product activation.
The main caution is that one ensures they use the correct "Edition" and it unfortunately does not support the new "Windows 8.1 with Bing" and "Windows 8.1 Single Language with Bing" "Free OEM Only Editions" at present. Finally it remains a .exe so media cannot be created from Linux or Mac OS and Microsoft have even locked out its use on both Windows XP and Windows Vista. Add your votes to leave feedback to Microsoft for the tool to fix the remaining issues and to ensure a smooth migration to Windows 10: