I had the Mini for a year. Not only was the price more appealing, but I thought the iPad 3 and 4 were really bulky compared to the Mini.
I wanted to use it for work, but the things I needed it for (handwriting, touch typing), were not as easy as I thought it would be. I thought it might've just been a tablets thing, in general, but I suspected it may have been due to the size. Part of that was because I needed to type on my lap, and the was not stable sitting in my lap. I thought if the rumors were true that the 5th gen iPad would be thinner and lighter, I'd give it a shot.
I purchased it online the night it released, but I thought I'd try it in-store to really make up my mind. I spent a good 20 minutes going back and forth between the display Mini and the display Air just typing and using a stylus on it for handwriting, and I felt it was MUCH easier on the bigger screen. I decided to keep it after it's done so well for me and I actually like the bigger screen for reading.