It was mind blowing at the time because Linux required at least 4-5 floppies to set up a text-only base system while QNX ran live from just a single 1.44MB.
When was that? You can still run from a single floppy https://github.com/Steve3184/floppinux and some form of that was available for ages.
Photon microGUI was included in that, and it blew my mind that you could literally kill and restart Photon without disturbing any of the GUI apps that were still running.
They also mailed a manual along with the demo disk, and I was amazed that QNX had built-in network bonding, amongst lots of other neat features. At the the time I was using Slackware & the linux kernel version was still 1.x, I don't think bonding came to linux until 2.x?