Can I read MIM first?

(of course I can read whatever I want... but)

Is Three Musketeers a prerequisite to MIM? I know who the characters are but is there vital information I need to know in order to enjoy it better?

I've of course seen the movies as well. Though you can't really say the Disney quasi-comedic version of Three Musketeers (with Keiffer Sutherland, Charlie Sheen and Oliver Platt) and Randal Wallace's Man in the Iron Mask (with Gabriel Berne, Jeremy Irons, Gerrard Depardieu and John Malkovich) are intentionally connected.

Having read both, what would you recommend?

Well, keep in mind that the events in the Man in the Iron Mask are 30 somethings years after the events in the Three Musketeers. Naturally, there will be character development. I, personally, prefer to read the entire D'Artagnon romances in order.

NO, YOU CAN'T! Remember that MIM was originally just volume three of ONE BOOK, which was "Vicomte de Bragelonne". In fact, it picks up in the middle of the action that leaves off in volume two (in the English translations called "Louise de Lavalliere" I think) and if you try to read MIM out of order you will not know what's going on at all. Besides, the Disney versions of the movies are more closely related to Cinderella than the actual musketeer books. You might as well not read it at all than read it out of order.