I was quite afraid of looking when it started circulating on Tumblr this morning because some people in fandom can be incredibly immature and even cruel when it comes to new Companions taking place of the previous Companion. But after seeing pictures of the actress and watching this recently released interview with her talking about this announcement, I kind of fell in love a bit. I already am loving her, I think she's adorable and precious and I think she's going to do just fine. For anyone who hasn't watched that interview, do so now, because so many have been sold on her by just watching that video alone.
I will miss Amy and Rory terribly, they have been my favorite Companions on the show by far. ♥ But I am curious as to who Jenna-Louise will be playing, her role in connection with the Doctor and what, as they are indicating, will be the big mystery that will entail with her.
My prediction: perhaps it has something to do with the First Question, the biggest mystery following him around for the last two series now, something that Moffat has been building up to something much larger for the Doctor to face. It's the only thing I can think of at the moment.