Highlights:

• Skyrim-style aiming while weapons are equipped (this might have been introduced in another patch, but I hadn't seen it)
• Weapon sets (weapons give you abilities, like in GuildWars 2. Each player can use any weapons)
• Armor/Weapons item prefixes (grant special effects & stats)
• Collectible Recipes
• Monsters (4 types, very dangerous)
• Massive cave systems (up to 5 tiers deep. Rewards & danger increase with depth)
• Linking & Triggering System (Their version of redstone, minus the redstone. Think "event handlers")
• Many new items
• Crafting system overhaul (Separation of crafting and building materials)
• Mining system overhaul (new material combining system)
• Salvaging system
• New props (some with cool effects, like huge fire blasts, colored flares, or geysers)
• VoIP in game chat that auto-channels you to your guild, as well as proximity

Here's the video:

Here are the patch notes:
https://forums.station.sony.com/landmark/index.php?threads/update-notes-17-dec-2014-let-there-be-monsters.51046/