Extra RAM and a better color gamut help make up for year-old guts.
There’s nothing new from Apple on the iPad mini 4. It is a last year device at this year’s prices. They did the exact same thing with the iPhone 5C. It’s still better than the shameful iPad mini 3, but either way, I wouldn’t recommend this to anyone.
But as nice as the upgrade is, there’s nothing here that wasn’t available for use a year ago. TouchID was already available. The A8 was already available. Apple obviously already knew that it was planning better multitasking for iOS 9, and it could have preemptively increased the amount of memory in the Mini to compensate.
If you want an iOS tablet, just get the iPad Air 2 (or for $100 less, the original iPad Air).