I've played with it a little on a couple boxes at home, and so far, I'm OK with it. There's some things I don't like (the "Tile" interface where you often need to go,) and some that I'm pretty much going "gimme, gimme, gimme, NOW!" for (Hyper-V Live Migrations with NO shared storage? Oh please, please, please, and thank you Microsoft!)
Active Directory isn't a whole lot different than it was before, the new server manager is "enh" but that may be that I've not used it that much yet (I keep going to the tiles, finding the "old style" management utility, and running that)
I did, overnight, upgrade my existing work Win7 box to Win8, to get a leg up on our clients who *will* be getting Win8 at some point, so that I / we aren't completely blind-sided by it...