Dragging a card is difficult for these reasons:
find the bit of the card that you can actually drag (I'm never too sure, sometimes it seems to be pretty limited, like just the edges). It would be great if this was clear - even if there was a dedicated corner, or a mouse pointer that shows when it can be dragged.
try to find a drop target. This is hard because you have to go above a card or the add card button before one appears - why can't you just move sideways; i.e. should be able to drop anywhere on a column. It's also hard/impossible to move up the page if where you want it needs to be scrolled to.
Jarring flicker after dropping the card: the card momentarily goes back to where it was, then flashes across to where you dropped it. This breaks the visual experience of dragging; it's sometimes hard to see whether it's moved or not. It would be much clearer if the flicker could be removed.
Hope these are helpful. They're little things but they make quite a bit of difference.
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screencast.

I feel "3" should be tackled first.
It has an unprofessional, cheap feel to it. Like if some beginner kid wrote this app tor a school project. You probably dont want to trust such a glitchy app with your company data?!
This might even create mistrust towards nextcloud itself.
(These are all unconscious thoughts of the user of course)
This should now actually be fixed in our vue rewrite. If someone is curious, we have a nightly build available in the releases of this repo that can be tested, but please note that this is NOT ready for production yet.
I just experienced the new UX, it's beautiful. Thanks everyone, this is a really great improvement.
Most helpful comment
I just experienced the new UX, it's beautiful. Thanks everyone, this is a really great improvement.