I really wanted to like Mama Mia! In fact, I was convinced that I would like it. I don't remember who talked me into seeing the stage version and I went to it in a very skeptical state of mind, both because of some snobbish bias against such blatently commercial theatre (I know, I'm a hypocrite) and by my life-long hatred of Abba music. But I liked the stage version of the musical. I had fun. I thought the way they managed to link the lyrics of the songs together into some kind of a coherent, if simple, story was clever.
Then I saw the previews for the film. Meryl Streep! Colin Firth! That girl from Veronica Mars and Big Love! Beautiful scenery! Mama Mia! I was so sure it was going to be great.
But it wasn't. Not for me. And in trying to figure out why, the only thing I can think of is that if you're doing a musical, you need to cast actors who can sing. Most of the women (save Julie Walters) sang quite well, but the men were sad. Especially poor Pierce who's the romantic lead of the film. It's hard to get emotionally involved in a story partly told by song, if you're distracted by the so-called singing.
Two other films in the fairly recent past were similar "types" in that they were stories that cleverly linked together well-known songs: Moulin Rouge and Across the Universe. These were two of my favorite films of the past 10 years. And I really think the difference was not only was there good storytelling and acting, but also good singing. The music parts were enjoyable and entertaining, not mildly painful and uncomfortable.
And I think that's why the stage version of Mama Mia worked so much better for me, too. They cast singers...
But what the heck do I know? Obviously my taste differs from most, because Mama Mia! has been a box office success, while the fabulous Across the Universe was not. Go figure.
(but I expect that's more to do with star power and major studio distribution, etc.)