I knew they wouldn't have mentioned my two favourite Amiga OS features: Pre-emptive multitasking and the Workbench screen model. At a time when PC users were still struggling with blocky DOS screens, the Amiga offered a virtual desktop type environment through workbench screens (which could be dragged up and down over each other or flipped backwards and forwards) and proper multitasking meaning that things in the background screens would carry on running.
The other OS feature is one that I only started playing with a couple of years ago on the ZX Spectrum. The ZX Spectrum has a fairly unique way of drawing the screen in monochrome 256x192 pixels and a 32x24 8x8 pixel colour attribute cell system. Ignoring the monochrome (which was what I used to use in the 80s) and manipulating 8x8 cells directly means that the entire screen is represented by 768 bytes of memory. This lets me play around with colourful 3d in ways I could only imagine as a kid. Sad, I know, but I'm just a big kid in the end.
You'll need an emulator called UAE (http://www.amigaemulator.org/) or a port like WinUAE (which comes with a frontend and is much easier), a Kickstart file for the right system (Kickstart is the name for the Rom and varied from Amiga to Amiga) and some floppy disk images for the games themselves. There's a WinUAE guide here: http://www.tweakguides.com/Amiga_1.html and a more general beginner's guide here: http://cpc464.back2roots.org/menu.htm
It's very different to modern OSes if you don't tweak around but as a modern alternative the Icarus AROS distribution (http://www.icarosdesktop.org/) provides a modern continuation of the Workbench experience.
The other OS feature is one that I only started playing with a couple of years ago on the ZX Spectrum. The ZX Spectrum has a fairly unique way of drawing the screen in monochrome 256x192 pixels and a 32x24 8x8 pixel colour attribute cell system. Ignoring the monochrome (which was what I used to use in the 80s) and manipulating 8x8 cells directly means that the entire screen is represented by 768 bytes of memory. This lets me play around with colourful 3d in ways I could only imagine as a kid. Sad, I know, but I'm just a big kid in the end.