Stay with iOS 7 imo.
It's not a huge deal (plus I like some of iOS 9s features like PiP/Quick Reply) but if I could go back to iOS 7 on my Mini 2 I would.
Why would you go back??
It's not major. An iPad mini 2 runs OK on iOS 9... just that iOS 7 felt smoother for me and seemed to have less stutters / app reloads.
It's like if you had a car that ran perfect, but you took it into a mechanic and afterwards it always had this sort of small shifting issue that wasn't there before and bugged you because you know it didn't used to have that issue. While you can still drive the car just fine, it's annoying that you can't go back to its original performance.
Personally, I hate that Apple's Accountants are controlling the Apple Product Catalog. Far too many products that should be retired are still being sold as "new" and something like the Mini 2 is one of the worst problems because it really struggles with 9.3.1.
I'm not saying Mini2 is bad. It's "good enough" for people with no expectations, but it is not a proper representation of the iPad experience.
It's not major. An iPad mini 2 runs OK on iOS 9... just that iOS 7 felt smoother for me and seemed to have less stutters / app reloads.
It's like if you had a car that ran perfect, but you took it into a mechanic and afterwards it always had this sort of small shifting issue that wasn't there before and bugged you because you know it didn't used to have that issue. While you can still drive the car just fine, it's annoying that you can't go back to its original performance.
This guy must not use his iPad mini 2 that much more must be not-so-sensitive to stutter. My iPad mini 2 stutters a lot when going back to the homescreen and while using the App Switcher. Quick Reply is stuttery too.This video specifically reviews the performance of iOS 9.3 on an iPad Mini 2