Saw it today: Some observations (scroll on by if you wish to avoid possible spoilers):
--The first part kind of dragged with too much plot exposition and not much musical exuberance. The plot is so irrelevant to this enterprise; what the movie was trying to do was go on and on about how tough Donna had it on her own. The play got the point across much quicker without the wallowing.
--Things started picking up with the song Mamma Mia; the larger tableau that a movie allows over a play helped here. Then Dancing Queen was the first real shop-stopper, about as good as it was in the play.
--Colin Firth had a good singing voice. Too bad he had only one song and Brosnan had three. Why they didn't dub a real singer over Brosnan is a mystery. He's asked to sing perhaps Abba's hardest song to sing, SOS. And he didn't really have chemistry with Streep.
--Speaking of Streep: Acting is also beside the point in the Mamma Mia franchise, and Streep was smart to recognize this, and to pick her spots. During the song where she is helping Sophie get ready for the wedding, she uses expressions and gestures to get across far more than what most actors can with words. And her singing voice was more than decent too. Her take on The Winner Takes It All, much more subdued than the belted-out version in the play, worked a lot better than the play's version.
--The Sophie character was as perky and appealing as the stage version, and she recognized that character isn't asked to go beyond that.
--The wedding scene, with a couple of bonuses you can do in a movie but not a play and very good performances, was better than in the play. A strategic switch in order of I Do I Do and Take a Chance on Me worked out very well.
--The movie had basically the same anticlimax ending as the play, and the postperformance music was truncated and not as good as the play.