Looking forward to upgrading from my mini 2. I know a lot of people think the mini is somewhat pointless now with the iPhone 6+, the air, and now the pro but I find the size a perfect compromise for a traveling tablet.
Took a look at it in store, definitely better than mini 2 but also slightly different than air 2. On pure contrast i think my ipad 3 was still better and more natural looking though.
I have one arriving tomorrow, but I stopped by an Apple store to compare the mini 4 and 2 side by side... I felt the overall same "betterness" as I felt when I first tried the Air 2 - Not sure if it's the processor or the memory, but the device is much more snappier and smoother than my mini 2 (which I really like, except for hitting my storage ceiling)
I also picked up a new cover - but there's absolutely no way I would spend $59 on a piece of silicon backing (where the case costs MORE than a Kindle Fire!) Maybe this is a test from Apple to see what level of ridiculousness their customers will put up with. I will personally shake my head at people who buy that Apple silicon case, just like I do on those who own a gold Apple watch