Zeug

1) Hyjal + BT trash suffer from missing loot
These are the missing BT Trash epic drops with their highest drop % per creature ID

Illidari Runeshield - 34011 - 1.8%
Shroud of the Final Stand - 34012 - 2%
Leggings of Beast Mastery - 31328 - 0.1%
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This is the missing Hyjal Trash loot = BT Trash Loot + missing loot from above + these 2

Pepe's Shroud of Pacification - 34010 - 0.9%
Hammer of Judgement - 34009 - 0.6%

2) Darkmoon Faire isn't spawned nor quests are available
3) Ashtongue Quartermaster isn't spawned and vendor sell table isn't complete
4) Arena Vendors have no vendor flag or are missing (not spawned at all)
5) Dancing Troll Village isn't spawned :p (hidden in Darkshore mountains)
6) ZG bosses that drop the class ZG trinket mats fight each other, also there should only be only one boss per week cycle (blizzlike)
7) Random boss spawns (like Karazhan opera event, Karazhan cellar boss)
8) I don't know exactly but I think not all warlock quests work (they need summons which have to be defeated)
9) I don't know wether it's Core or DB related, but loot from chests isn't working, so you can't finish the alliance part for rogue's thistle tea quest
10) The Locking Stone in the entrance from AQ Temple wall in Silithus should be removed, else you can't get to the instances
    ( Serverwide event to open and unlock AQ isn't necessary imo)
11) Quests which need creature loot to be tested with a certain quest item don't work (for example http://www.wowhead.com/?quest=1016, intact bracer don't drop at all)
    I don't know if that's a Core or DB bug
12) Vendor items changed since 2.3: for example +4 stats on rings entchant is now buyable from lower city quartermaster and not scale of the sands
    Other Items might be changed aswell, also in 2.3.3: Shattrath has a new ambience sound