Its useful for filling in small gaps and repeating patterns which CAF wont do properly. It also attempts to replicate the lighting in the scene, which is clever.
But if you try to use it for larger replacements, it starts to have issues, and its impossible to make it work well. Even with the enhance detail feature in the variation thumbnails, you get low res results. I know you can replace selections in smaller chunks to get them higher resolution, but you shouldn't have to. I know Adobe are struggling to keep up with all the cloud processing, and are even considering a credit system to slow down the flow, but people are PAYING for this feature. I know you can use it to expand the edges of an image, but what's the point if you're just expanding into sludgy low res space?
For now its a handy patching tool which, hopefully, they will boost up going forwards. But knowing adobe they wont. There are features in Photoshop which are 15 years out of date and they haven't shown any sign of updating them. Adobe are going to have to embrace Ai and improving the usability of their key programmes if they want to compete going forwards. They keep on putting useful simple features in Lightroom instead of photoshop and its just starting to piss me off. Photoshop is the real deal, Lightroom is the autistic little bastard brother. Stop showering him with gifts just because hes thick.