Let there be light!
On the right of the LCD there's a button that allows you to turn the backlighting on and off. Unfortunately they have forgone brightness levels this time because that is a feature that can be enabled under software so that each M setting delivers a different colour of your choosing.
The LCD itself is housed in a tilting gloss casing and really is the centre piece of the keyboard with your eyes always drawn towards it (especially when it's on).
Around the back next to the cables are two standard powered USB ports for your peripheral enjoyment. It's good to see Logitech not making the same mistake of the G15 and recessing them into little nooks so that nothing would ever plug into them.
Following the cable back somewhat, we can see it's a combo USB and power jobby so your power cord piggy backs in on the USB cable from behind your PC. Out of sight, out of mind.
Stacking the G15 and the G19 up, we can see that they're almost identical in width with only the G15's key layout being about 1cm wider over all.
And in terms of height with the wrist rests on, they're pretty much the same.