For pure entertainment with no pretensions of being anything more, this was just the ticket. Better than Gosford Park, in my opinion. Julie Andrews, Colin Firth, Sophie Thompson are all excellent. Even William Baldwin was just right. (As much as I want to NOT like those Baldwin brothers, they are pretty good.)
This was based on a Noel Coward play, so the idea was to take a stageful of characters and shake them up to see what happens. In this case, as Julie Andrews's character says "Not much, really." And yet, for an hour and a half, servants are scurrying, doors are opening and slamming shut, British aristocracy is pulling out all the stops to maintain its way of life, and Hollywood stars are swooping in to shake things up.
So ignore the lukewarm ratings of the professional reviewers and just enjoy good writing, fine acting, and a story that won't change your life.