This episode was good.
I've never been a big fan of the Little Mermaid so I wasn't that excited about Ariel, but Joanna Garcia did a good job and now I'd like to see more of her. Like some other people here I think Ariel and Eric's scenes were the weakest part of the episode, they were just bland and I think it's because we have seen nothing on the show to make us root for Ariel and Eric as a couple, the whole "love at first sight" is a pretty weak motivation to explain their feelings specially compared to most couples on the show, who developed their relationships over time: we have seen how Snow and Charming met and fell in love, the same with Rumpel and Belle, Regina and Daniel were already a couple when we met them so it was easy to see how much they loved each other, same for Peter and Ruby.
But with Ariel and Eric all we get is "I saved his life and I fell in love" and the cheesy "I dreamed of you", even in the Disney movie Ariel had a better reason, she had observed Eric for a long time and she liked what she saw, and Eric saw Ariel for a second after she saved him (and he remembered her voice), which explained why he was interested in Ariel when she got her legs. But in the show they made it very clear that he was unconscious all the time and never saw Ariel. Besides, it's hard to develop any chemistry with an actor you just met, and Eric is not that interesting, at least for now.
And the costumes of the ball scene were awful, I think it was the short skirts, in all the ball scenes we have seen so far the dresses were always very princess-like, very elegant, but this ones looked more casual and they looked really out of place.
Look at me, I can't stop nitpicking even when I like the episodes
I like that Regina was just a fake Ursula, Lana was having the time of her life when she was doing that scene and it shows, and I love Yvette Nicole Brown (how I want to see her in Community once again) so I was really happy when I realized she is voicing the real Ursula.
The rest of the scenes were good, I liked a lot the cave scene and the fact that the darkest secret was not about something bad you did in the past but something about yourself you don't want to admit, it was very touching when Snow admitted she wanted to have another chance to be a mother, it's obvious she really wants to raise a child and no matter how much she loves Emma, their relationship will never be what Snow wants.
And Neal has go back to his usual bland self. Hope they change that because I really want to like the character.