I use folders very heavily and have a nested hierarchy of over 500 folders. The Paperpile implementation of folders somewhat easier to use than Zotero’s, which I used for many years; but there are still some important gaps.
The most important is the inability to locate a particular folder in the hierarchy. It would be great if there was a search function for folders in the left-hand column, as there is for tags. Lacking that, I’ve figured out a klutzy workaround: I select an item and press the “F”[older] key. After about 8 seconds the entire hierarchy drops down from the top. There’s a search function there, but it hides all but the folder you’re searching for, so you still can’t locate it in the hierarchy. What I do instead is to use the Chrome search function, which does find things in the folder dropdown without hiding the rest of the hierarchy. (This method has the added advantage of making it relatively easy to add an item to multiple folders: you can do several Chrome searches without closing the dropdown.)
Another use case is when I select an item already in a folder – I can see what folders it’s in, but again I can’t locate the folders in the overall hierarchy, which is sometimes important. I notice that if the left-hand folder hierarchy is expanded, the item’s folders will be highlighted (gray). But as far as I can see there’s no way to expand and contract that hierarchy without clicking on every node. A relatively simple solution (I think) would be a keystroke that expands / collapses the left-hand folder hierarchy.
The long delay in expanding the dropdown hierarchy is also a hindrance. It’s great to be able to add an item to a folder by typing (part of) the folder name, but when it takes so long each time it gets frustrating. I don’t know if that could be speeded up.
Overall, though, I really like the Paperpile experience – thanks.