Hubby and I went to it last night and really liked it.
As far as the southern accents go, I think they were "overdone" because that was the style of the movie. It wasn't supposed to be realistic. And, since most of the movie happens 50 years ago, maybe the accents were sronger back then.
ETA: and some actors in the movie, such as Ewan MacGregor and Helena Bonham Carter are not American, so it might be easy to see where an accent might be "overdone."