A woman can be an Imam of women but not of men, you see Aisha and Fatima are known to be among the greatest women of all time and they followed the Prophet (peace and blessings of God be upon him) in prayer. What does that tell you? If they are context to be like that, what about us?
Classically women were scholars of hadith and they were massive scholars in this field. A scholar is at a higher degree than an Imam. Its a religion of shyness and it better for a man not to have see a woman bend over in front of him!
She can lead women in prayer but not a mixed gathering