For all of Milton's religious and socially backward personal views I actually loved reading Paradise Lost, but not for the way Milton probably ever intended it to be looked at. There is so much to the work which make readings so varied and abundant with meaning ready and waiting to be plucked (reference intended).
I was reading Milton's epic poem for my English Literature class and preparing to write an exam on it (done earlier today), so I was taking especial care to read with a couple of core specific ideas in mind in conjunction with the work (especially ideology, as that was the title of the course). In my personal reading of the book I ended up considering a lot to do with gender roles and free will.
I liked Milton's utilisation of blank verse, until then never used in English narrative poetry, especially to this extent, though used in drama frequently. You do have to remember that it is a poem, and thus it does often require either reading outloud or listening to an audiobook to get the metre and the enjambed flow of the language and imagery. I ended up actually lying in the bath reading it outloud to myself with Apocalyptica playing in the background once or twice. The first 3 or 4 books arguably are the most interesting of the 12 it is divided into, and the last 4 or 5 is almost entirely composed of conversation between Adam and the archangel Michael, and this does drag on a bit (which is where an audio version helped me greatly).
Taking this into consideration it is no wonder that the Romantics believed Satan to be the true protagonist of the poem, who has fallen and ventures out on a journey to revenge his fate and that of the other fallen angels. He is successful in his task, but ultimately fails as they are punished again. I prefer to see him as a false protagonist figure (much akin to Marion Bates in Alfred Hitchcock's Psycho) who is almost wholey abandoned as a key figure as Adam and Eve are more introduced. I much like William Blake's idea that "[Milton] was a true Poet, and of the Devil's party without knowing it," which backs the reading of many of the Romantics that Satan is the real protagonist, and that there are a multitude of other possible readings of the text other than what Milton actually intended, which was to "justify the ways of God to men."
I spent much of my time considering the ideas of fate and free will within the book, and in my reading I came to the general opinion of fate being present throughout even when God predeicts that Adam and Eve will fall, but by free will and not by fate. In my particular reading it would also support an anti-Milton-esque view on the submission and weakness of women, which I found particularily interesting, but that really isn't the type of topic that many will find interesting here...
God as a character I found rather banal and stiff. Milton goes to such efforts to make his Satan animated and an active hero to his own cause that in comparison God just seems droll. Satan definately provides more literary and plot interest throughout the book; God provides more of the theological questioning behind the events of the book, and Milton's particular depictions of characters.
Thats just some of my thoughts, but I have to sum up that Paradise Lost is an epic poem worth the reading. It sparks much in the realm of philosophical and theological debate and pondering, even just in a literary context (personally I am not religious in the slightest but as characters they are very interesting when refering to religious texts). Anyone interested in literature should give this one a read, though I suggest getting an audio version to help with at least the first reading. ;)