They should have released both. A new raid (as we expected) and the Arena.... it would give us some variety. They know the amount of time between HoW and 'Comet' is too long though... so they are holding the raid back. Probably going to charge for it too, since it won't be 'part of the DLC' (that was mentioned in his update... it was a hard decision, but -blam!- you and your raid).