Comment by formerly_proven

There's multiple things to this.

One is the complete change in how the app is structured. Many feel going from tabs with purposes and distinct UIs to one "mono UI" where you navigate between the sections by scrolling a lot is a regression. (On the other hand, the new UI can be customized a bit)

The other is the pretty severe performance regression. The old Photos app was mostly fairly smooth when it came to scrolling and zooming. In the new Photos app literally every time you start moving even a few cm on the timeline it's choppy and stuttering for a second. Zooming is likewise a stutterfest. That's pretty bad because it's just an extremely obvious and reproducible straight-line regression.

And finally there's changes like how the timeline is now always wrapped to a full last row, which means anytime a photo / video is added, the whole timeline is re-wrapping. For reasons only known to Apple this rewrapping will happen visibly and stutteringly when you open the Photos app even if the picture was taken five minutes ago. That change is incomprehensible because clearly people spent a bunch of work adding all those stuttering animations, yet nobody questions how obviously retarded it is to have an infinite scrolling timeline where _appending_ an item causes everything to shift? And then you don't even make an effort to hide that, but instead show a grid of photos when opening the app, then notice "oh, the user took a photo some time ago! How very unusual! Let me wait half a second and then reshuffle everything on screen!".

It's the exact equivalent of having ads pop in or layout shifts two seconds after page load. It's extremely and very obviously bad.

These are the kinds of thing that make it obvious that none of the people working on this software actually use it. It's the kind of garbage you expect - and get - from throwing JIRA tickets over the fence to some random lowest bidder sub-sub-contractor five continents away.

And that's the level of quality you get in one of Apple's "flagship use case" apps (how many iPhone ads focus on the camera? Most of them).