I was impressed with this show. Not sure whether or not it will get another season, but I'm not sure that it needs it? Obviously I would love if it does, but Killgrave seemed like THE villain for her and I'm not sure that she'd have the same type of connection with any other villain that we saw between her and Killgrave.
I thought the side characters were well developed. And it's rare that you see a show dedicate as much character development to the antagonist as this show did to Killgrave.