I tried the thing for half an hour in our Apple Store. And I really tried to like it. And it's close. Is it worth 4000€? That's something one really has to clear with their own conscience / wallet. It's an early adopter device with a very limited production run. Of course it's super expensive. Which is a fair point, but shouldn't go into evaluating the device from the get go.
The key problem I have with it is weight. Just the bulk of additional inertia it adds to the front of your face is super awkward, and after just 15 minutes there are visible marks around your eyes from the sheer pressure this thing exerts on you to stay on your face. Maybe an additional headstrap fixes a lot of that, but they didn't have one on hand.
The accuracy of the hand gestures is mind blowing, although there is pretty noticable latency - but I think unless you are gaming with it you will kinda learn to factor that in. Eye tracking was a bit hit or miss at first, but once you get used to it it's stunningly intuitive. And it's leaps and bounds ahead of anything else picture quality wise. Plus: it's maclike snappy. This alone is very impressive and a sharp contrast to most other head sets I've tried.
Carrying a battery on a pack is pretty weird, yes, but I get why they did it - and you kinda forget about it. Which might be a mixed bag, because you don't wanna get tangled up with your 4K device, I guess. But ... the.... uhm... face avatar? .... uncanny valley in the extremes, and I don't really get this feature. I get it conceptually, yes, but how much hardware went into that thing solely for that feature? And the first thing I wanted to know after I saw it on my wife was: how do I deactivate THAT? Forever? Pretty please? Stahp!
I think if Apple would be willing to simply cut this feature alone, saving some of the camera hardware inside, getting rid of the screen for it and swap the glass front for much lighter aluminum .... They could cut a good chunk of the price, and really reduce the frontloaded weight of it without making the device any less useful for the wearer. It would also save some battery life, which is a plus considering the battery life is rather limited.