Good addressing of concerns raised.
>> Personally, 12.04 with Unity was what truly sold me on Ubuntu, and I suspect the same will be true for far more users than they lose over it.
This is a correct observation (at least my own anecdata verifies it too).
Huh? You press the windows key, and start typing in the name of what you want to look for. I find it far easier to find things with Unity than before.
> it hinders productivity more than any of the other offerings
I was planning on installing a tiling window manager when I first installed Ubuntu 12.04, as I really want the desktop environment to not get in my way. I stuck with Ubuntu because contrary to your experience,to me it's the most productive UI I've used in the last 20 years+.
> makes it impossible to find out what applications you have (since software store apps and normal apps are held separate)
"dpkg -l" like in any Debian based system. I find this a ridiculous complaint from someone who has gone back to Debian, though - any way you can find this info in Debian is available to you in Ubuntu.
> once Gnome fallback is disabled/no longer ships, will be shoved down users' throats more than WinRT or Launchpad are.
As long as Debian ships alternatives, going back is fairly easy. But as it stands, there are plenty other alternatives for Ubuntu too, shipped by the community.
Personally, 12.04 with Unity was what truly sold me on Ubuntu, and I suspect the same will be true for far more users than they lose over it.