I have installed Piwigo 2.3.3 about 2 weeks ago for trial and uploaded thousand photo to it, though I read from the forum that 2.4 should be improved but it is my first time to use Piwigo so want to try it on a bug free environment.  I have sum up some comments as my usage mainly is a Personal Photo album.

1. Album Sorting
Allow sort by 'Album date": Most of my album is created on some event, that mean photo in the album is taken on same day, a sorting by descending album order is quite logical to me.  Thought it could achieved by manual order, I will have several hundreds album, it will be unmanageable.  Another suggestion I read on forum is divided the album by year, but it seem a little bit odd to me.

2. Album Pagination
As I have quite a lot sub album in a album, it will easy to navigate if got pagination ( I knew there is ticket for this, but seem it original target is 2.3)

3. Synchronize Folder out of web root
Because I use same brand of camera, the photo file name pattern is fixed, that is easy to guest.  Although Piwigo don't have a Photo file protect mechanism, the random string append to file name at web upload make it difficult to guest. Seem the Multi-size function in 2.4 will create different size version, that will have similar effect if the sycn folder is not located under web folder

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Other comments is about Back end UI

4. Albums -> Manage -> Manage Album Photo:Currently it is linked to "Batch Manager - Global Mode", maybe added another link to "Batch Manager - Single mode" for easier go to edit photo attribute in Albums Manage.

5. Albums -> Manage: Add "Add photo" link at album navigation.

6. Albums -> Manage -> Edit Album: Allow choosing album thumbnail.  Piwigo make the album thumbnail photo in Photo edit page, it should be flexible for set thumbnail to different album, but I think most of the time is choosing thumbnail within the album.

7. Albums -> Manage: Beside have function icon(edit/manage/delete...) at sub album list, maybe add same set of function link under the Parent Album name, I am often click & click, when down to lowest leave album, I have to go back to upper leave for some operation.

8. Batch Manager -> Global Mode/Single Mode: Some confusion on the name single in the batch, for me, seem Global model is "Batch Operation" on file, Single model is "Batch Edit" on file attribute.