For folks who use the Liquify tool to retouch faces, this will be a huge boon. On any detected face in an image, Photoshop breaks down the facial features and provides tools optimized for shaping them.
I have horrible problems with keeping my horizon level and frequently need to crop portrait images to landscape with a larger aspect ratio, so this will be incredibly useful for me (when it comes to Lightroom, at least). When it works, it's a fast way to preserve the image's dimensions when rotating.
If you don't rotate and simply drag out the handles it automatically performs a content-aware fill. It's really useful to pad photos when you're too close to an edge.
The ability to find typefaces that resemble those in a photo is really handy. But Adobe's algorithm needs to do a lot more learning before it's usable.
The advanced tools get their own workspace, with a revamped interface that is supposed to make it easier and faster.
One of the improved integrations with Adobe Stock is the ability to license an image directly from the layers palette in Photoshop or from the canvas in InDesign and Illustrator.
The new Premium option consists of curated photos aggregated into collections. Better options for more money. You can see the difference in the options for a search on "cats."
You can now define a fixed header, dubbed a "masthead," for your Portfolio sites.