The problem isn't the tech itself. Getting a pretty darn clean 4k output from 1080p or 1440p, at a small static frametime cost is amazing.

The problem is that the tech has been abused as permission to slack on optimization, or used in contexts where there just isn't enough data for a clean picture, like in upscaling to 1080p or less. Used properly, on a well optimized title, this stuff is an incredible proposition for the end user, and I'm excited to see it keep improving.