Do this: Find all of the reviews of the iPad2 when it launched that talked about how "awful" the screen is. You can't. Because they didn't. And this was in the day and age of the "Retina" iPhone 4, so don't give me the "it was a different time, and now things are different" crap... Retina existed, and everyone STILL thought the iPad2 LCD was excellent.
Is Retina better? Yup.
Is the Mini, with it's BETTER ppi than the iPad2 "horrible" "unusable" "painful" or any of the other silly descriptions I've heard? Heck no.
As someone who's had one for 3 months now, and ALSO has had a Retina version of everything else (and has 20/20 vision), I can honestly say the screen on the mini is fabulous.
It's not AS good as a Retina, but it's still fabulous. People just want the top of the line everything, and if something doesn't have it it automatically becomes crap.
Unless they make the Retina mini as thin and light there is NO way I'd upgrade (unless it has other things I want, which it may...).
Don't let the whinings of the "I'd trade it all for a little more" crowd convince you of anythig until you see it for yourself. It's BETTER than a screen that literally had no complaints, even when Retina already existed in the wild...