I think all of the casting so far has been spot-on. Corden and Blunt are a really great pair, and I'm pleasantly surprised that Baranski will be staying in the cast following the reading; she's terrific. I am wondering how this will interfere with her filming of The Good Wife, though.
As much as I usually like Amy Adams, I just didn't buy her as The Baker's Wife. She tried and I admired her for that, but it didn't do much for me. She would have made a great Cinderella back in the day, though.
The kiss from the Prince also can play on the whole idea of class segregation. Even in a fairy tale world it would be easy to understand a common baker's wife being flabbergasted that The Prince would want to kiss her, no matter what she looks like.