For 3 hours my eye could not used to the new look of 3.5. And even I do appriciate new features "in engine", I switched back to 3.36. Sorry.
I've been seeing the look of Paint.NET 3.36 every day for 2-3 hours for many months and in order to change this visual habbit my brain has to made a huge amout of work, but I do not have mental enenergy of such an emotion impulse to fulfill this visual habbit change. New features give much less positive emotional energy, than the new look generates negative emotions.
The last, but not the least. Designer is a creative job, and when I feel negative emotions, when I feel pain in changing my visual habbit I produce worse pictures or even could not produce anything, cause my imagination refuses to think, to create, to work, when I feel hurt every time I look at new icons.
I only have to pray, that there is some coder, which feel the same and think up some way to replace some resource file with the old icon set.