The Ancient Cistern is without a doubt the greatest dungeon in Skyward Sword and among the most well designed in franchise history. It was a division between the mundane and the fantastic with the latter underground part completely unexpected.
With the Ancient Cistern, Nintendo once again had the element of surprise on its side. Every previous water temple was just that-a dungeon filled to the brim with large amounts of water. This was true of the Water Temple in Ocarina of Time, Great Bay Temple in Majora’s Mask, and Lakebed Temple in Twilight Princess. The Ancient Cistern certainly changed things up with its underworld undead theme. While I had already previously spoiled myself via trailers, the sights and sounds were still equally fascinating and horrific to behold.
That being said, the lack of more water in the dungeon was also one of its shortcomings. Previous water dungeons revolved around challenging the player to think in new dimensions and truly push their brains to the limit. The Water Temple in Ocarina of Time, for example, was low on combat but earned its notorious reputation through its bamboozling water level altering puzzles.
The dungeon probably won't be remembered too fondly down the road but it certainly featured some interesting mechanics which I'd like to see in future installments.