In reply to David Esrati.

So you basically say that hunting around settings in 10 screens (with no preview of changes) is a better UX for the novice than the customizer? And if you have been that long around you must remember that around 2.0 - 2.2 there was a preview iframe as part of the edit screen, so even the concept is not very new to wordpress.

There are many faults with it, but nothing will be better without it.