For me it comes down to optics. I've tried damn near every VR headset ever made, including many that never made it to production, and they all suffer from the same core issue: poor optics. Even industrial headsets that costs thousands are still using flat screen and lenses with fixed focal points (with few exceptions, but even then nothing truly extraordinary).

Current optical designs mean that there is a large out of focus area when you look anywhere that isn't forward. That's just never going to fly for the general consumer. For VR to truly go mainstream you needs an optical system that is truly sharp, edge to edge. That probably means some kind of active optical system (like reverse OIS) or some kind of magic lens that currently only exists in theory. Instead what manufactures keep doing is trading off FOV for sharpness.

If Apple has implemented a new optics system here I think they have winner and the industry will change overnight. If it's the same as current designs just a little better it feels DOA to me.

I'm optimistic because I can't imagine Apple, of all companies, putting out a headset that's blurry at the edges.