I'll confess, I've never read the books. I have however seen several productions of the play onstage and I prefer this beautiful miniseries by far. All of the productions I've seen before cast elderly men with cute lines but no charisma. The choice of Richard E. Grant for the Scarlet Pimpernel surprised me, but he did a wonderful job with it. I was very surprised by his performance, as I'd only ever known him as a supporting/character actor (like Twelfth Night and Gosford Park).
As a life-long Elizabeth McGovern fan, I can't help but love her. She's a fantastic actress, but whoever did her hair should be guillotined. For a really beautiful woman, they hid it well under ten pounds of brown wig. It sadly resulted in her looking much older than she actually is, but fortunately this isn't the case for the entire movie (at least at the end she gets a haircut!) But her striking features still shine through and her beautiful performance far outweighs that hairstyle. She also manages her accent very well (she's originally from Illinois) But, well, I watched the whole miniseries just for her, so I can't help but think she's the real star.
Ronan Vibert is another actor I've liked for a long time, and he did a fantastic job as Robespierre. Martin Shaw's Chauvelin got on my nerves a bit, but he's fine. The big surprise was sweet little Emilia Fox in the role of Minette. I'd never seen her play a villain before, and was pretty impressed by it. All in all, I really enjoyed this miniseries, and highly recommend it.