I don't know - my LR dealer offered a 2-hour one-on-one session with my Discovery 5 to go through everything - the pressers aren't getting that benefit, they are probably getting a 15-minute orientation, if that. The Land Rover iGuide is the manual now - there's no "book" - and it's available on your phone, and it will walk you through configuration of stuff with a visual mode that shows the dash and lets you tap on items to get information on it.
When I test drove the Defender, I spent maybe 5 minutes fiddling with the drive modes and I had it figured out - while the interface is different than the knob on my D5, the symbols are the same. There's one button you press on the dash - a physical button in between the two climate knobs - that pops up the menu on the screen, then you turn the left climate control knob to select the mode, and there are menu buttons across the bottom for customizing steering, throttle, and differential behavior. There are still physical buttons to control ride height as well.
I think most people who will buy a Defender for its intended purpose will get used to it pretty quickly.