Not only is Ahn'kahet visually stunning, but it gives you a glimpse into the story of Yogg-Saron and his relation to the Scourge and other forces. It's a little repetitive in some places (the first boss is a bit boring), but it also houses some of the best 5-man bosses we've seen yet. The final boss, Herald Volazj, is the embodiment of the technical advances Blizzard has made with the gameplay in Wrath of the Lich King. I almost feel bad mentioning him at all, because I've been running Ahn'kahet repeatedly with people who have never done it before. Seeing them wig out the first time they do the boss is awesome.