The Verge: Mac OS X Yosemite Preview

Here you have a fairly detailed preview of Yosemite, which just yesterday reached the Developer Preview 4 stage, and reportedly is going to be an open beta today.

I installed Yosemite right after the WWDC release, and I must say I am impressed by its maturity. I had very few, minor bugs thus far, and I am using it in my work computer without any significant hassle.