Apple Weather is still missing some of the data that Dark Sky exposed, like cloud coverage percentage and other niche info. I also find the UX a little worse, as I like more data at a glance. But you can tell they're using the Dark Sky backend, as it has the same bugs that Dark Sky had, like slowing loading map tiles which sometimes fail altogether. And there was the time they accidentally reenabled the Dark Sky API after an Apple backend deployment. :D