An excellent review:
[T]he most impressive thing about the iPad Air 2 is not its screen or its thinness or its camera, though those are all quite lovely. It’s the speed, and the extra RAM. Using the iPad Air 2 while flipping around from app to app feels like an entirely upgraded experience from performing the same tasks on my iPad mini 2. You learn to blot out the time you spend waiting for apps to open and Safari tabs to reload, but once you spend time on a device that doesn’t need to take those pauses, they become obvious. Painfully obvious.
I wish the iPad mini 3 featured all these same improvements, but it doesn’t.
[W]hen I look at the power that Apple’s dropped into the iPad Air 2, I’m convinced that the use of iPads as everyday tools will just keep on growing. These devices are in their infancy; the iPad has existed for less than five years, and is now on its sixth generation. They’ve come a long way, and in some ways the software hasn’t really kept up with the hardware.