I've never played as a female trainer before, but I do like her design.
Odd how I'm seeing the consensus in this thread is not liking her design lol maybe it's because I haven't played as a girl before that I like it.
Unless it's an RPG with a unique character (established name, backstory, personality, etc. like FFXIII), it's a little odd for me to play as a female, I guess because I don't identify as one? Though I have role-played as them before (and still do. As a writer, I'm trying to learn different identities to portray them accurately).
The boy is just...too Pokemonish. By that I mean exactly what everyone else has said: he looks completely interchangeable with the last few protagonists.
I'm considering getting both versions (which would be a first for me) and play as one gender for my main version (barrel through for the story) and the other gender for my other version (explore the hell out of Alola).