Wintersday TLDR notes from sneak peek articles

 PVE:

• All wintersday daily events are on a 24 hour completion timer once activated.
• 275 new crafting recipes, these are not all wintersday related.
• Wintersday themed chests in Black Lion Trading Company.
• build snowmen around the world much like pumpkin carving (probably part of the monthly achievement)
• Tixx will drop presents from the sky when he flies around Tyria
• Plans and materials will be present in said drops.
• Jumping puzzle: Winter wonderland Jumping puzzle (frostbite debuff timed mechanic)
• PvP Minigame: Snowball mayhem capture the flag pvp game (3 skillbar classes - Scout, Heavy, Support)
• Activity: Bell choir rockband style 3 player per team mini game at the Lions Arch Snowglobe. (3v3 music battle?)
• New scaling dungeon accessed via the golem airship. Each city will have content relevant to the home race and content will build as Tixx flies over each home town. (Dungeon is aimed at a 30 minute completion time)
• Final instance event is a Horde mode meets tower defense minigame. (This sounds awesome).

WvW and PvP:

• Siege weapons will be wintersday themed.
• Holiday finishers are available.

Source: http://www.reddit.com/r/Guildwars2