With some more natural red hair I think she could have been a good MJ, but she's looking perfect for Gwen too.
I'm really hope there's a strong bond between Pete and Gwen in the reboot. I want to feel horrible when she inevitably dies and I want to feel Pete's pain when he fails to save her. (oops, did I forget the spoiler tags? :lol)
Hopefully, MJ plays second fiddle in the film and the Peter/MJ relationship blooms toward the very end of the movie or even only starts in the sequel. I'm praying this is the case, since Gwen was cast so quickly and we haven't even heard any rumors about who will potentially play MJ.