I plan to wait on W10 due to the forced downloads. With my Verizon data plan and the typical 100MB+ multiple monthly updates I want to be in control of when the data is downloaded and not when MS wants to download.
I also want the ability to hide/block updates before they happen and my understanding is that with W10 that is only possible post install. There are just to many past MS invalid updates to suit me.
Forced updates do solve the issue of OS issues due to outdated versions and is certainly valid for that reason. I just don't want to be on the leading edge of installs and I want to control the downloads. But that's me and this might work for most users who are clueless anyway.