Nice to see something different. I'd also expect to see complaints soon about screen problems in the area of the fold but it is the first generation of these sorts of devices.
I'm guessing the folding form factor fones 4F will become pretty common in a few years. So we'll get 4F5G phones (maybe even W3E4F5G).
I cna actually see quite a few people chosing to upgrade for that sort of change.