"How much tweaking went into that?" Literally none. This is the default desktop. I installed Fedora 23 yesterday (and it looks very similar to Fedora 21, which

"How much tweaking went into that?" Literally none. This is the default desktop. I installed Fedora 23 yesterday (and it looks very similar to Fedora 21, which I had before, which I think looks like default Gnome 3). The theme, background image, fonts, color scheme, calendar settings, everything is from the standard Fedora Workstation install. I'm lazy and rarely spend much time tweaking things (my terminal and my vim have some customization, but even that's minimal), particularly now that it's all very nice looking right out of the box.