I'm a fan of Jane Austen and have read several of her books, including "Emma." I've also seen many of the movies that have been made from her books over the years. I tend to think of them - particularly versions of "Emma" - in terms of who played the title role. This is Romola Garai's "Emma," and the two others I've seen are Gwyneth Paltrow (1996, American film) and Kate Beckinsale (1996, British TV film). There's a significant trick to "Emma:" she is both obnoxiously meddlesome and very charming, and the trick is to balance it to the point that the viewer will believe that a man as sensible and practical as Mr. Knightley would love her. Paltrow's version failed spectacularly: her Emma was distinctly unappealing. Beckinsale (somewhere in between her vacuous turn as Hero in Much Ado About Nothing and becoming an almost full-time vampire) is my measuring stick here: she tramples peoples lives and charms in equal measure, so much so that Mr. Knightley could not help but love her.
This version has a number of things going for it: Jonny Lee Miller as Mr. George Knightley, a nearly four hour running time that allows the inclusion of all the subplots and characters, a very good supporting cast, and a very good writer (who took some liberties with Austen's text, but generally did a good job of it). It's a fairly good production, but I have to admit I'm not a huge fan of Garai herself, which is a bit of a problem as she's on screen most of the time ... Ultimately I was left feeling somewhat ambivalent to something I know intellectually is quite a good production.