Please vote this up and feel free to share tips and links that point to issues and migration tips from Mavericks to Yosemite on your primary development machine.
Upgraded to Yosemite a few hours ago on my Macbook Air 11" and have had no problems at all. Homebrew works fine. My primary languages (Erlang & Elixir) run fine. Edited files with vim. But I've only done a fraction of my work for now (today).<p>Expect some sort of "visual overload"[1] once you upgrade. Too much of color (It felt like the interface was done with crayons). After a few minutes of work it'll feel normal.<p>The phone-calls-on-mac and turn-on-iOS-personal-hotspot-on-mac features will only be available in iOS 8.1, which is slated for an Oct-20th release. I am looking forward to these two features.<p>[1] - My friend called it that :)
If you use Asepsis then you'll get a message saying it's incompatible and won't be migrated, however if you reinstall it'll work just fine.