Johnny Appleseed be praised! Caitlin McGarry at Macworld:
Why this matters: More RAM helps the iPhone do more things at once, allowing you to have more apps open in the background and more Safari tabs open before you're forced to reload them. In the iPad, the extra RAM will power features like Split Screen, which lets two apps run side-by-side simultaneously. That’s another reason why we think the iPad mini 4 has 2GB—the small tablet supports all of iOS 9’s multitasking tools.
Where the boost in RAM matters most to people will vary, but where the benefits are seen will be easy for anyone to spot. The multitasking app switcher, 4K video recordings, and iMovie edits should make good use of an extra gig in the iPhones, particularly for the iPhone 6S Plus.
The iPads Mini and Pro will improve for Slide Over, Split View, and Picture in Picture. These are ways that you can have two apps and a video playing on display at once.
What I want to know is if 3D Touch demands a lot of RAM. If this is the case, the iPhone 6S Plus might not benefit as much as we hope and still encounter the issues we see on the 6 Plus. ∞