Been using a Mini for 5 months; original iPad for 3+ years. Now, iPad Air in the mix as well.
A series of back and forth, pro and con thoughts...
Really like the Air; noticeably faster, lighter than original. (The amazing thing, though, is how good the original iPad still works. It's only the occasional slow web page loading--a couple of seconds--or in contrast to the Air--that it seems a laggard. Most all apps I use still work fantastically well and that includes several graphic intensive ones.)
Now, that light weight of the Air can fool you. Its center of gravity lies away from your hand(s) and is thus more prone to tip away from or slide out of your hands.
The Mini, with a smart case (Fintie), weighs about the same, but is a quick grab, carry, hold, use device--and with case closed easily fits in and is managed by one hand. The Air not so much.
I really like the Mini for ebook reading. Just the right amount of text. The iPads really show too much. The Mini is also great for Scrabble, Sudoku, etc.
However, the real estate on the Mini is limited for web browsing--and the text is too small. Pinch-zooming works but only at the cost of scrolling left-right. That is solved for many sites by using Reader, the built in enlarger within Safari. But many, if not many most, sites do not have it. Which makes the Air better for the web--at least for my uses.
Now, it's worth noting that Apple dropped the in-Reader font control in iOS 7, so the iPad Mini 2 won't be able to use that as an easy solution (we're still on iOS 6 on our Mini). There is a work-around using the Accessibility settings (however, some older iPhone apps then have EXPLODINGLY LARGE type).
Personally, if we only had an iPad (any #), I'd wait and get the iPad Mini 2. The wonderful thing, the fun thing is that you'd then have the two sizes. They're great for doing different things, different uses.
Having both then for some time, you could decide whether you wanted to upgrade to the Air and have it replace both the 2 and the Mini--or just end up with three!