I don’t really think Milton was trying to create a feminist symbol in his Eve, but I believe he did, however subconsciously. The woman we meet at the beginning of the text personifies many stereotypes about women – she’s vain, unthinking, and emotional. Her subservience to her husband seems inevitable and absolute. Though God says she was created with free will, we don’t see any examples of this before her Fall.

But when she does Fall, it’s on her own terms. Though Milton’s Satan certainly manipulates Eve during the conversation, she clearly does not regret her actions, wondering if she should even offer Adam the fruit or keep it for herself:

But keep the odds of knowledge in my pow’r

Without copartner so to add what wants

In female sex, the more to draw his love

And render me more equal, and, perhaps

A thing not undesirable, sometime

Superior: for inferior, who is free? (Milton, 9.820-825)

I think that last line really gets at the crux of Paradise Lost. Every conflict in the novel is about power – who has it, and how they can get more of it. Eve is born at the very bottom of the totem pole, barely above the beasts Adam has been given. Yet it’s her thirst to rise up that drives the main conflict and climax of the novel. In many ways, Eve is the protagonist of the story, growing and changing more than any of the other major figures.     
Milton lived in the 17th century, and was not known for valuing women. Yet it’s hard for me to believe that a man as educated and well read as him would glorify the ignorance of pre-Fall humanity. Instead, I think he highly valued human intelligence, and the discoveries being made during the Scientific Revolution. So while paradise may have been lost, I think he believed that Eve gained something that day – and I think he was glad that she dragged men along with her.