Okay, so Julia Jones is older than Leah's character...so is Rob older than Edward (especially when they do BD!). Leah is supposed to be older than Bella anyway and I also thought of her as coming across as older than her age because of what she's been through. So I don't think Julia's age is an issue.
I love that Julia's been talking in interviews about really getting into the books and the advantages of having all the characterisation & background in the books to back up the script. I think she's going to do a great job as Leah.
http://www.boston.com/ae/movies/article ... es/?page=1I thought her hair would be shorter as Leah though...not that that was Julia's decision!