Theres the graphical glitch that anssi-laiho mentioned—which is really weird. also I've been having some weird errors with sample files i've been loading. They're all single waveforms from the adventure kid waveforms collection — so it could be specific to the way his files are encoded. I'll be honest though, I can't quite put my finger on it but I've been getting more random errors in kyma since I've installed High Sierra. I'm seriously considering rolling back to el cap or something I trust a little more.
This of course is aside from the feeling that with every new osx/macOS update, There's a sense of relinquishing more control to apple, more bloatware (honestly—why do I even need siri?!) and having to search out ways to reduce the general cpu footprint of the os. I use a combination of onyx and some shell scripts I've stolen off github—mostly just defaults write commands. Yeah, I'm probably gonna roll back to el cap or something. The more I know about tech, the more of a luddite I become!