Hard real time (so latency guarantees), microkernel (and they actually mean it, so your device drivers can't hose your system), standardized networked IPC including network transparency for all services, ISRs at the application level.
Sadly not anymore, Qnet was removed in 8.0
In general QnX was commercially mismanaged and technically excellent. I'm imagining a world where they clued in early on that an open source real time OS would have run circles around the rest of the offerings and they'd have cleaned up on commercial licensing. Since the 80's they've steadily lost mind and marketshare though I suspect they'll always be around in some form.
I've also noticed that all of the message passing system calls still accept the node ID. Are there plans to open up this interface to allow for implementation of custom network managers, maybe? I'd be very interested in exploring that.