I hadn't read much on the game before I started, and I kept calling that there would be a
PH dungeon in the game (I just had a feeling, I'm not sure why), and when I finally got to the Silent Realms, I was like, "There it is!" and I loved it. I haven't done the Eldin one yet (just finished the Lanayru one), but I really enjoyed the two I've done so far. They are mandatory, but you get cool items from them anyway.