Do you mean as soon as they went with the dark theme?
Suddenly everything feels slower and less crisp.
Back in the day when the tools, image and properties were all separate windows (this was common on UNIX) and it had issues with a lot of window managers. It was fiddly and awkward. However I would still prefer that over the current state.
Luckily for me my art skills are so crap; I can use mtPaint and not notice any decrease in my productivity / quality XD