I think the gym leaders in Black and White are all really cool. They actually get to do stuff outside of their gyms and even after 5 generations they still manage to hold their own and be cool and interesting. Elesa is easily one of my favorites out of the new gym leaders.
I think the supermodel motif is a neat angle. All the gym leaders seem to have some sort of hobby or other job, and I think the Pokémon universe's take on a supermodel is something we've never seen before. And she's about what I'd expect from that premise, but that's certainly not a bad thing; she's still very pretty and elegant and captivating, and even pretty funny, I think. Her catwalk-themed gym in Black 2 and White 2 is a riot, and I think in both games Elesa really steals the show during the brief tenure you spend in her city.
I actually really like her B2/W2 redesign, and I think it's especially appropriate for a supermodel to radically change her look like that, but I like her original design just a little bit more.
So, yeah. I'll readily admit that Elesa made it into the month mostly because she's nice to look at. But she is quite nice to look at, and remember; I said she was one of my favorite new gym leaders.