I've been using it since DP3 on my machine and no serious problem so far. Its weird that some folks complain about Safari but for me Safari is working great.
Yosemite might become my defacto fav for a long time, but it needs to be released first and then bugfixed several times. It is to Mavericks what Mountain Lion was to Lion and Snow Leopard to Leopard -- and yes, IMO the latest really stable version is 10.8.4
I've become such an Apple fan that I plunged head first.