I am getting an iPad mini only because I have a macbook air so there is too much overlap. The mini will be a great companion!
I've been debating this same question for weeks. I currently have a iPad 3. I'm definitely getting a iPad 5 and giving my wife the 3. Debating whether to also get the Mini 2. I currently use a Kindle Paper white as my main e-reader and think a retina Mini might make a more versatile replacement.
James
Retina or not retina I can't see any point of getting mini. That is why I have my iphone for. I think Jobs would never allow it as well as iphone 5C.