I like the layout, with the side-by-side dials rather than front and back. Pressing the left button changes modes, and you can remap the secondary function on the fly by holding its button down. It defaults to ISO sensitivity.
By making the top dials multifunctional and mappable on the fly, Leica could get rid of extraneous buttons on the back. A single press of the Fn button lets you change a particular setting; holding it down lets you choose a different setting to be the one-touch option.
To keep the clean lines, Leica eschews such niceties as a USB port for charging. So not only do you have to tote the charger, you also have to tote the power cord, because it doesn't have built-in prongs.