It's always difficult to take a familiar piece from one medium to another. Mama Mia is one of those few shows that everyone knows, so the task becomes doubly difficult. There's also the casting question: Actors first or singers first?
No one will launch their singing career with this movie -- especially Pierce Brosnan -- but all the performances were well within the acceptable range. Meryl Streep may be the only actress of our time who could carry the Donna role in this film.
I could do without the slow motion special effects. It seemed like they were added just because they were available.
Having said all that, it was a fun way to spend the afternoon with the woman I love. The encore scene was an absolute hoot and sent the audience off with one last blast of feel good mojo from the ABBA era.