I have been hosting it locally for a couple of months now.

Stuff I like:

  - The mobile app is quite friendly
  - It supports "automatic upload" (after opening the app)
  - It supports deleting pictures from the device after uploading (to save space... much needed on the wife's old iphone)
  - The pictures are stored hierarchically on the filesystem
  - Very lightweight (the whole docker setup uses less than 128MB of RAM)

Stuff I'm not a fan of:

  - The web interface is "okay". It could use some modernizing.
  - When there's no more space on the device, the app fails to upload new pictures, but gives no error message.

All in all, Piwigo is a solid 7.5/10 for me, but I'm watching and testing some other active software such as https://immich.app/