Not too enthused with Arrietty but I do like the name : Ariel. I think it's a nice name.
Not sure about Arrietty, it sounds a bit difficult to pronounce not so bad but a bit doubtful about it.
But i like Ariel more, the pronunciation is more stylish & the name sounds pretty.
I don't like either. I was around after Little Mermaid came out and it seemed that a lot of people were naming their kid Ariel. An "a" name that I like is Aria.
Sounds like twins someone is trying not to name Timmy and Tammy.
There is an economist who writes a column for the Wall Street Journal named Dan Arietty. It sounds like a last name. Not sure about naming a child after a Disney character.