It should live up to the cost and the hype. The content in the expansion pack looks like it's going to be absolutely massive in size; there's quite a lot of new dungeons getting added and they sound like the quality of Deadmines, Shadowfang, and Gnomeregan (not Molten Core). There's even a faction-city/dungeon sort of like in both EverQuest games where the dungeon is a massive city that multiple factions rule over and war in. You get to basically choose which faction you want to side with, and their dungeon turns into your home-base for the region, and the other factions turn into your dungeons to raid (and PvP, I presume, since other players will use them).
Reminds me of Calimport for some reason from the Forgotten Realms world.