The girl simply looks awesome by design. By comparison, the male looks a little bit like a wuss. He certainly looks better than the males of previous generations, by the "urban" look to him, but he just doesn't suit my tastes.
His hair kind of puts me off a bit, I prefered Brendan myself, but I am sure I shall grow to like him.
The girl,however.. erf, I hate the little side strands of hair and her two antennae-like spikes sticking up from her ponytail. At first I was completely thrilled at having a female protagonist with a ponytail,as it is my favorite hair style for females and I almost ALWAYS use it for my own female characters in RPs, but seeing the design of her hair kinda took me by surprise,almost gagged, but I shall grow to simply ignore the bits I do not like and rejoice that she does in fact have a ponytail.
He really reminds me of classic Red, which is pretty cool. I was neutral to Gold's new design, Lucas, and Brendan, so it's finally good to be able to play through a Pokemon game again without wondering if I should have chosen the female one.