Read Mighty Avengers when he joins. That's why he's so freaking awesome!
EDIT: To go further, Pym is a mad scientist. He could be one of the worlds most destructive villains if he could, but he's a timid and insecure good guy. He's likable, as long as you're not a moron who goes "LOL HE SLAPPED HIS WIFE! WORST AVENGER EVAR!!!"