Carly's got a lot going for her: she's got the vocal talent, she's good with song choice (CeCe hasn't been great at that in the house), she's cute without being "inaccesibly" cute, and she is (or certainly seems) very humble, and thus overall likable. Her parents are also likable, unlike some bitchy mothers we've seen in the past.
I think the one thing that could do her in is the pressure and workload. We've seen that before in other shows, where the young ones simply burn out toward the end. Alison Iraheta on Idol comes to mind - had a lot of the same stuff going on: down-to-earth cute, pleasant personality, huge natural talent, but at only 16, the pressure was too much, and you could hear her faltering as the season went on.
If Carly's parents can help her keep it together and not over-exert herself, I think she's got it in the bag. Then too, I don't think X-Factor is quite the same pressure cooker that Idol appears to be.