I upgraded my Macbook Pro to Mavericks, and everything works fine except Pathfinder, which is a sort of Finder replacement, and Xmarks for Safari, which is a bookmarks sync application.
I don't use the Macbook Pro for anything audio-related except I just put a trial version of Ableton Live 9 on it, which worked fine, no problems.
I just ordered a tiny little Macbook Air for work, which will have Mavericks preinstalled, so that will give me more hands-on time with the new OS, when that arrives later this week.
Overall, I'm fine with it, but as both El culto and Antdude said, it's better to be cautious about upgrading a system on which you need to do important work, especially an in-progress project. It would be terrible to be unable to access something you were in the middle of, and for this reason I usually don't upgrade my main computer until some times has passed. May primary Mac Pro is stuck on 10.7 because Mountain Lion doesn't support my video card... so by the end of the year, I'll finally be upgrading my main computer after nearly 10 years with this Mac Pro.