"Fun" is the best word to describe this film. "Plot" or "content" may not be. As I've heard with the on-stage musical, the biggest drawback to the whole thing is that the writers seemed to have found any excuse to toss in another Abba song. (And I do mean ANY excuse, including some really useless romantic side story lines.)
Still, Amanda Seyfried is outstanding as Sophie. She brings some real honesty to the character. And watching Pierce Brosnan belt out a tune was worth more than a few laughs. I have to say, Meryl Streep didn't knock me out of my socks. Watch for the Greek Chorus, though. They'll pop in at the best times.
Overall, it was a fun, rock-out on-screen musical--just don't expect to have your life changed by watching it.