She's an Ice/Psychic-type with a distinct style all her own. She's also one of the original Pokémon, so she has a great deal of nostalgic value. To see her competitively empowered with powerful new stats and a possible new ability, and to wrap it all up in a fresh take on a familiar design, is exciting indeed.
But the one I'm starving to see is Mega Aggron. He looks amazing in the balloon shot -- now I want to see him in full color and detail. I want to see him in battle, and then I want to see the Sugimori art. Mega Aggron looks like a perfect evolution of the Aggron concept, exactly what you'd expect him to look like after he goes "Super Saiyan" (or in this case, "Super Shredder").