As far as patch notes are concerned, these are huge but there's enough meat here to set the community talking. The update is primarily made up of two things: a new Golem based event in World versus World and profession changes. When it comes to the Golem event, the patch notes state the following:

Hop into World vs. World between July 17 and July 24 to experience our newest special event, Golem Rush, where siege golems are better, faster, and stronger!

During the special event, all golems will be supercharged and have the following effects:

All siege golems in WvW no longer require supply to construct.
All siege golems in WvW will deal 100% additional damage to other golems and players.
All siege golems in WvW will move at 100% additional movement speed.

The Mist War Summons bonus effect will be available to all players during the event and will apply the following:

+15% World Experience Bonus in WvW
+15% Experience Bonus in WvW
+50% Magic Find in WvW

In addition to the above, there's a fair few changes that affect most professions. The biggest change is probably to the Necromancer and Chill, with the condition now stacking to 5 and Chilling Darkness trait receiving a significant nerf. Considering Chilling Darkness is only used by Well Necromancers combined with dagger off-hand or Well Of Darkness, its now been nerfed into oblivion. Well of Suffering only lasts 5 seconds and blinds every second for the duration. Necromancers will now only get chill once. My assumption here is that from internal testing, Chill is proving too strong for the Reaper. Either that or someone at ArenaNet is fedup of getting caught by Well's in World versus World. You can read the full patch notes here, or below. 

NEW FEATURES AND CONTENT
World vs. World

• Hop into World vs. World between July 17 and July 24 to experience our newest special event, Golem Rush, where siege golems are better, faster, and stronger!
  
  • During the special event, all golems will be supercharged and have the following effects:
    
    • All siege golems in WvW no longer require supply to construct.
    • All siege golems in WvW will deal 100% additional damage to other golems and players.
    • All siege golems in WvW will move at 100% additional movement speed.
• The Mist War Summons bonus effect will be available to all players during the event and will apply the following:
  
  • +15% World Experience Bonus in WvW
  • +15% Experience Bonus in WvW
  • +50% Magic Find in WvW

BALANCE, BUG-FIXING, POLISH
General

• Chill condition now stacks to a maximum of 5.
• Tutorial maps are now using the megaserver system.
• Fixed a bug in which the attack targets of some bosses could not be hit by melee or ground-targeted attacks.
• Fixed an issue that prohibited world bosses from being critically hit from some attack locations.
• Fixed several significant graphical issues with the Monk’s Outfit.

Items

• Wurmslayer’s helms and gloves can now be used in the Mystic Forge with an Anthology of Heroes to create ascended gear with different stats.
• Small bags of spirit shards can now be opened in the Heart of the Mists.

Profession Skills
General

• Fixed a bug that caused skills that convert boons to conditions to not properly convert stability to fear.

Elementalist

• Conjure Flame Axe—Flame Leap: Updated the skill facts to properly list a burning duration of 8 seconds rather than 7 seconds.
• Empowering Flame: Fixed an issue that caused this trait to permanently give 150 bonus power to the elementalist.
• Arcane Precision: Adjusted this trait’s cooldown time to accurately reflect its listed internal cooldown.

Engineer

• Fixed an issue in which miniatures were able to trigger med-kit bandages and antidotes.
• Med Kit: Fixed an issue in which the total number of appropriate condition stacks was not being removed correctly.
• Thermobaric Detonation: Fixed an issue in which this trait set Evasive Powder Keg on recharge.
• Incendiary Ammo: Fixed an issue in which this skill applied an incorrect amount of burning.
• Grenadier: Fixed an issue in which this trait allowed players to hit more times than intended with grenades.
• Throw Bandages: Fixed an issue that prevented this skill from removing the full stack of a condition as intended.
• Grenade Barrage: Fixed an issue in which this skill gained unintended functionality with the Grenadier trait.
• Cleansing Synergy: Fixed an issue that prevented this trait from removing the full set of conditions that it was intended to.
• Kinetic Battery: Fixed an issue that prevented this trait from working properly with Detonate Mine Field.
• Smoke Bomb: Fixed the skill facts to display the proper pulse interval.
• Throw Accelerant: Fixed an issue that prevented this skill from removing the full stack of a condition as intended.
• Throw Stimulant: Fixed an issue that prevented this skill from removing the full stack of a condition as intended.
• Automated Medical Response: Fixed an issue that caused this trait to have a 10-second cooldown instead of the intended 90-second cooldown.

Guardian

• “Hold the Line!”: Fixed an issue that prevented this shout from playing its voice-over audio.
• Perfect Inscriptions: Fixed an issue that prevented this trait from granting light aura when using Signet of Resolve or Signet of Courage.
• “Feel My Wrath!”: This shout is now usable underwater.
• Wrath of Justice: This trait’s recharge is now properly affected by the reduction from Perfect Inscriptions.
• Symbolic Avenger: Fixed an issue that allowed this trait to deal higher damage than intended.

Necromancer

• Dhuumfire:
  
  • Fixed a bug with this trait that caused the skill facts on shroud skill 1 to omit the damage within a range of 600.
  • Corrected an issue in which the Dhuumfire version of shroud skill 1 would deal less damage than intended.
  • Fixed a bug in which Dhuumfire was a shorter range than shroud skill 1.
• Unholy Martyr: Fixed the description of this trait to specify that it draws conditions instead of removing them.
• Chilling Darkness: Added a 5-second internal cooldown to this trait.
• Plague: This skill no longer inflicts bleeding every second while it is active. Instead, it inflicts 10 seconds of bleeding when it is first activated. When traited with Master of Corruption, it inflicts 4 seconds of poison.
• Mark of Evasion: This trait now only activates if you are in combat.
• Last Rites: The portion of this trait that prevents allies from bleeding out now only applies to allies while you are not downed. The bonus healing power is applied regardless of state.
• Consume Conditions: Lowered the number of self-applied vulnerability stacks from 10 to 5.
• Vampiric Presence: Fixed a bug in which the Vampiric Aura effect applied by this trait allowed it to steal life on skills that did not actually hit.

Ranger

• Healing Spring: Fixed an issue that prevented this skill from working properly with Rune of the Trapper.
• “We Heal as One!” and “Strength of the Pack!”: Fixed an issue that prevented these skills from working properly with Rune of the Trooper.
• Zephyr’s Speed and Vigorous Training: Added a 15-second internal cooldown.
• Beastly Warden: Fixed an issue that allowed players to taunt targets that should not have been affected.
• Light on Your Feet: Fixed an issue in which this trait provided an incorrect increase in condition duration.
• Call Lightning: Fixed an issue that prevented this skill from properly applying daze.
• Cold Snap: Fixed an issue that prevented this skill from applying its initial chill.
• Aqua Surge: Fixed an issue that allowed this skill to be fired twice while traited with Nature’s Vengeance.

Warrior

• Whirling Axe: Fixed a bug that caused this skill to grant 180 precision under some circumstances.

Structured Player vs. Player

• Disconnected players in Unranked and Ranked Arena games will now show on the scoreboard and party UI with a disconnected icon.
• Players will no longer be in combat on respawn if they died from attacks instead of from a finisher.
• Players can no longer rally from NPCs in Legacy of the Foefire.
• Adjusted the health of NPCs in the Forest of Niflhel and Legacy of the Foefire.