Juana was surely a strong woman (I never thinked she would be a submissive bride) but still will be much easier to control than Isabella so a man like Ferdinand would be likely able to get almost everything he wished from her
Easier to control, maybe. But as I said, she seems to have an opinion of herself (I think she might have a lot in common personality wise with Elizabeth I - mom's accused of adultery, rumored to be a bastard, playing hokey-pokey with her position in line to the throne). I don't say she'd necessarily be as intelligent as Liz was (Hell, most sources don't seem to tell us much with regards to what sort of education Juana got. Although I could imagine that as heiress to the throne/king's only child it may have been of a better quality than Isabel's was.