@Pirate_Freder
Did you get yours yet ?
I'm still happy with mine. One thing I learned: 7" phone, especially with 16:10 screen ratio, is too big for one-handed use
I'm 6'2" (187cm) and I previously handled 6.5 inch phone, where I could reach all corners of screen (with some stretching). I can longer do it with this beast, mainly because it's much wider (16:10 vs. 16:9).
For past few days, I was obsessing with improving single handed use, and I found some ways. There was nothing in software like "one handed" Samsung options. The one decent dialer that has it is Swipe Dialer Pro.
In keyboard department, A.I. Tablet Keyboard has everything I need: numbers row, split landscape option and resizable floating keyboard.
For launcher, I settled with Apex, for its added gestures: I have double-tap to turn off, swipe down to pull down notifications, up to pull QuickSettings. I also keep ButtonSavior menu near right edge of screen - all of these free my thumb from traveling to far edges of screen.
One usability problem is the location (and tiny size) of power button, you will find yourself hunting for it. I set volume buttons to allow waking (in GravityBox), but it only works 50% of the time, something to do with different sleep stages.
One app that helps here is "Awesome On Off" - it can turn the device on if you hold it under certain angle. It's also not 100% reliable and it costs some battery power, as it keeps watching the gyro sensor in the background. I'm still testing it, but I already know that it's alternative, Gravity Screen, is not good on this device - the proximity sensor is not the way to control it.
The back cover of the phone creaks during use, it adds that "cheap" feeling. It comes form compromise of thin form factor and ability to replace battery so I guess we can't complain.