It’s a breath of fresh air compared to other gray UI’s that are so boring that it makes me want to fall asleep. Seriously, I think they couldn’t have chosen a more boring color than gray.
Ed: I just checked, almost all my other software, even obscure stuff has got the Dark UI Option turned on. But I agree with you, in that people like different things so we should both be able to choose our preference rather than have one or the other.
I agree regarding the icon colors. It’s fresh and lively. It also greatly helps recognizing the icons. Regarding the toolbar background color I think it’s best to use the OS color. This way the user can customize it and it fits well into everything else. I would be fine with dark UI being an option inside SU too, but don’t care that much and certainly wouldn’t want it by default.