I used an iPad 2 with my wife, pretty nice - I loved it over my Air and 4S. When the mini was announced I didn´t feel interested, in fact I skipped the part when I watched the Keynote. Beginning of last month my wife was awarded with an iPad 4 and iPad mini. We gave the 2 away and my wife wants to use the 4, while I got the mini. When I unboxed it, I had the first wow-effect. It is so much more light and the build quality and design is amazing. I fell in love right away, while my wife had the wow-effect with the performance and display of the 4. From the first day I could not hold off my hands from the mini though. It is amazing to have such a device in the hands and I also think the screen has won in comparison to the 2, but of course the retina of 4 is another category. Since last month there is not a single day without the mini, it is so much more fun and convenient compared to the 2, 3 or 4 or the iPad. Grab it in the morning to quickly look at the latest news or check some websites. The heavy usage is in evening for me, browsing, skype, games such as Asphalt racing & Real Racing 3 now. The performance is decent, but could need a little bump. I absolutely underestimated the mini, this is an amazing device I am even thinking of upgrading to more RAM now. 3/4G is not an issue, since I use the iPhone to tether the Internet connection. The point is actually not that I was lucky in getting a mini for free, but more that I like probably many others underestimate it. The iPad 4 is great in performance & screen, the mini is just so much more comfortable to use and better in design in my opinion - you just want to hold it in your hands. Battery is another positive thing, yesterday I had 15,5 hours of usage before recharing, running 6.1.2 - unbelievable.
I would give the iPad 2 away for the mini in a blink of an eye - it is amazing, very happy with it.