I am quite surprised really, as I really didn't rate her live performance on the first live show. And yes she was better in her audition process, I felt 2shoes for example have been more consistent and better singers overall.
So for her to be so popular means there must be something else about her other than her singing ability, perhaps it is because she is in the papers a lot more? Popularity does seem to depend on familiarity.
I still think the fairest option show have been the lad since he was voted out over Frankie and so should take his place. This would leave the judges with the same amount of acts as they did, and leave everything almost the same.