Here's the link to the most current patch notes. For the Lazy, I've copy/pasted the DK parts.
Players may now create death knights on any realm once they reach level 55.
Bonus Armor: The mechanics for items with bonus armor on them has changed (any cloth, leather, mail, or plate items with extra armor, or any other items with any armor). Bonus armor beyond the base armor of an item will no longer be multiplied by any talents or by the bonuses of Bear Form, Dire Bear Form, or Frost Presence.
All multi-rune abilities generate 15 runic power.
Anti-Magic Shell: The cooldown has been lowered to 45 sec from 60 sec.
Blood Aura now grants 2/4% instead of 1/2% healing.
Blood Presence now grants 2/4% instead of 1/2% healing.
Bloody Strikes will receive extra bonus damage from Pestilence.
Bone Shield: The mitigation has been reduced from 40% to 20%.
Corpse Explosion: Damage increased substantially, added 5 sec. cooldown, and changed cost to 40 runic power.
Dark Command: Range increased to 30 yards.
Death Knights have access to unique death-knight only facial textures and skin tones. These can be selected at the character creation screen.
Death Pact now grants 40% instead of 20% healing.
Frost Presence: The bonus armor has been increased from 60 to 80% and magic damage reduction increased from 5 to 15%.
Heart Strike no longer has a haste debuff but will now be able to strike two targets.
Horn of Winter now has no cost and grants 10 runic power in addition to its stat buff, but has a 30 sec cooldown.
Icebound Fortitude now reduces damage by 20% instead of 50%. The amount of damage reduced increases with bonus Defense (to about 35% for 540 Defense, but can go higher).
Night of the Dead now grants 40/70% passive area spell avoidance to your pet in addition to its current effects.
Outbreak will no longer receive bonus damage from pestilence. The bonus from Plague Strike and Blood Boil has been increased slightly.
Pestilence no longer has a 10 seconds cooldown.
Raise Dead has now been split into two spells: Raise Dead now raises a ghoul or pet ghoul (if talented). Requires corpse dust if no humanoid corpse is nearby. Raise Ally now raises a fallen party member as a ghoul and has no reagent. Available at level 72. This should now last for 4 minutes.
Rune of the Stoneskin Gargoyle (two-handed only) now grants 25 Defense and 2% Stamina.
Rune Strike: Damage decreased from 200% to 150% but threat increased to 150% from 100%.
Shadow of Death: The duration has been changed from 45 seconds to 25 seconds.
Unholy Blight had had its cost reduced from 60 to 40 runic power.
Wandering Plague will now properly reset after being cast.
Vampiric Blood: In addition to its current effects, also adds 20% health temporarily.
Will of the Necropolis will now reduce the damage of any attack that takes the DK below 35% health by 5 /10/15% instead of boosting armor when wounded.
Missing from this list are the changes to Gargoyle, Necrosis, and Anti-Magic Zone.
Gargoyle, we knew this was coming, but wow. It looks like its base damage is being hit for 25% which will take its DPS from ~ 1000 to ~750. I can live with that, don't like it but on the grand scheme of things shouldn't be more than 50 dps on a boss fight by itself. The duration on Gargoyle just got cut in half.
Necrosis is getting buffed to do double the damage which may make it more desirable than Impurity. Pending testing on PTR and Live this may or may not be worth changing some talent points.
Anti-Magic Zone is also taking a hit. The up-time of the zone is getting reduced from 30 seconds to 10 seconds.
Needless to say there are a ton of Chicken Littles on the forums decrying the end of the Death Knight, the end of Unholy DPS, the end of Unholy Tanking.
THERE IS NO REASON TO GIVE UP UNHOLY TANKING OR DPS
Is that clear enough?
The losses in IBF, BS, and AMZ are made up for in the buffs to frost presence. Not to mention we can cast AMS 25% more frequently when taking lots of magic damage.
Fully talented AMS nets us 20% baseline magic mitigation in frost presence after the patch. The armor improvements will also encourage the use of BS for when we know we will have spikes. I have also seen reports that the glyphed BS will be 6 bones instead of 5. This will allow more uptime.
We are losing DPS on bosses with the nerf to Gargoyles. This is offset in two ways, talented properly, our ghouls will have better survivability which will increase their contribution to your DPS and Necrosis is getting buffed. For the average player like you and me, we are not going to see any real difference in our abilities to kill a boss.
Now I want you to take a deep breath, relax, and go kill some mobs.