"Anyone accustomed to using an iOS device with a Retina display will immediately notice that the iPad mini doesn’t have one: Pixels are clearly visible. It’s very much like looking at an iPhone 3GS. It’s a good, bright screen, but if you’re a Retina convert, you will not be pleased."
This, in my opinion, is the possible dealbreaker. While the display on the iPad mini should appear better than the iPad 2's display (163 ppi vs 132 ppi), I think I've been spoiled by the Retina display.
My original plan was to keep my Retina now-obsolete-3rd generation iPad at home for couch browsing, comic reading, and the occasional game (also since my daughter has recently discovered anime on Hulu+) and employ the iPad mini for work. However, my eyes might not be able to tolerate that change.