She's more than a one-dimensional character but she's not a three-dimensional character. She does have a more developed personality than Aurora and Elsa. However, she's not fleshed out, she's mainly just negative traits that are played for painful laughs about her wanting love, she doesn't develop, and they're really shoving her quirks down our throats so much that (unlike with Ariel, Rapunzel, Mulan, and so forth) her character doesn't get the chance to breath and we don't just get to enjoy her.

I don't know she just doesn't FEEL like a full developed character to me. She's a quirky ditz and she loves her sister...that's it. She feels cartoony sometimes, like a caricature. I still love her though.

She is so close to being three-dimensional that it kills me! There's only one problem, her motivations and reactions make no sense! Why does she love her sister so much? (And no, because they're sisters is not a sufficient answer. I love my brother unconditionally, but only because we have known each other for so long, and have a mutual give-and-take relationship). Especially after not talking to each other for 15 years, and literally being killed by her sister? She seems to have no resentment towards her sister at all. Hell, she's willing to literally throw her life away for her sister. But why?!?! And it's not even like she develops to that state, she's willing to climb an entire mountain even after her sister completely froze Arendelle.

I personally think that she's the most selfless of all the princesses what with everything she's willing to do for her sister. But that doesn't make her three-dimensional. On the contrast, it detracts from her believability.

^ maybe it's because her sister is the last remnant of her family? also they seemed close as little kids and maybe that just stuck with her? also, she's pretty stubborn and idealistic, i could see her clinging hard to what they once had and really refusing to accept things as they are because it's not how she wants things to be? that's my take on why she's so loyal to elsa.

i'm kind of torn on whether she's 2D or 3D; i'd have to watch frozen again and i really don't want to. :)

She's got an upbeat, quirky side and a self-conscious side, I guess. But her character feels too forced to be three-dimensional.