The Serenity movie was great. I only saw 1 or 2 of the TV episodes and loved the movie. Not sure how continuity held up with the series, but i knew enough to follow it and enjoy it. My wife had not seen any of the series and she liked it too. It's a throw back to what Star Wars was originally ony a bit more gritty.
Not a good movie for children under 10 in my opinion.