The key is that you don’t have to search for sense out of all new stuff. You can use only these new features that you find being helpful for you.
For example buses in V5 are only graphic objects while in V8 can know what wires they contain, but I don’t use this feature and still use buses as graphic only objects at my schematics - my (your) choice.
In V5 after first "update PCB from schematic’ I spend relatively long time dividing footprints into groups according to their belonging to different blocks in the schematic. Having both schematic and pcb widows opened I moved footprints one by one based on showing me each of them at schematic. In V8 I just select a block after block at schematic and use hotkey ‘P’ at PCB - not more than minute and I have all footprints divided as I want. This one feature would be enough for me to go from V5 to V8.
The other is that to make a PCB pictures as I want (element rectangles with references inside on the background of gray copper) in V5 I had to export separate layers to svg and then collect them together using inkscape. With V8 I get these pictures from KiCad without a need later to collect all layers together. Only what left to be done with inkscape is:
but this is only three hotkeys to be used there.
You can look through following threads:
to find features you would like to use. All that are of not interest to you, you can simply ignore.