Affliction got some nerfs, but is still holding strong and currently looks like it'll do well in 5.2
Demonology got lots of buffs. Much rejoicing here. Looks like it'll be roughly on par with affliction (depends on fight, player skill etc).
Destruction saw some buffs, but the gosac nerf hurt its cleaving ability a lot. Single target dps has gone up, but cleaving (which was its niche) has gone down.