Making this thread just to consolidate the information and have a single reference about that.
Forst official patch notes plus some datamined informations are on DiabloFans, like HERE.
Well, buffs for many less used ability and some mechanics rework - discuss
As for DH - we already knew of the DEX rework which is fine; most notable things are a switch from poison to cold damage for many abilities and buffs all around to less used ones like Strafe, Rain of Vengeance, Impale. Plus the new Shadow Set bonuses look way better than before (permanent Shadow Power is huge).