Vertical flip phones are dummyed. If that’s your aesthetic then good for you I guess but they’re pretty pointless IMO, as a guy it doesn’t matter if my phone is a long bar or a shorter thicker bar, it’ll still fit in my pocket with some extra room.
Horizontal foldables make more sense, but the inner screen ratio is kind of wack for doing things I’d do, which is mostly watching videos. I guess if you’re an insane phone power user who does productivity shit it’s all good but it doesn’t really work for me. A lot of apps also just don’t work well with the inner screen and waste the extra real estate. This is why I like the TriFold and the rumored iPhone Fold, they have 4:3 aspect ratio inner displays which are more appropriate for media (especially older media), plus they’ll work well with the existing library of iPad apps
Tech wise I’d say they’ve come most of the way, durability has become less of an issue, the weight and thickness is now the same as a regular bar phone, and with this generation the crease will hopefully be a non-issue. Now all we need is Corning to figure out how to make glass that folds and Apple and Samsung to figure out silicon carbon batteries (that the bad drivers already use but YMMV with them) and they shouldn’t really have any more drawbacks