The key question is whether it's 2D or 3D. If it's 2D (which I understand regular screen-plus-mirror things to be), then it's not much different from a screen,

The key question is whether it's 2D or 3D. If it's 2D (which I understand regular screen-plus-mirror things to be), then it's not much different from a screen, except that it takes up much more valuable floor space and is going to be a lot more expensive, while also horribly breaking immersion if you're nearby. If the frame/box really add much immersion, then some solution that can sit flat on a wall while still appearing to be a cabin (recessed into the wall) would likely be a lot more successful, as it can "create" instead of eating real estate.