I looked online after the film, and sadly, I had a hard time finding a good review -- but that's what I'm about to write.

I freaked when I saw the trailer for it before "Sex in the City" - OMG! A movie version! That, and "The Dark Knight," both in the same summer?
So, I'm not a film critic -- I don't go to the movies with a pen and paper to jot down notes throughout the experience. I go for, well, an "experience." I judge a film overall, and don't let one or two bad apples in it spoil the whole thing.
Meryl Streep was wonderful - I wasn't sure what I'd think of her, but she played a tough, but fun, broad ("Donna") who's had a hard life raising her daughter Sophie and keeping a hotel running on a Greek island. She sang well, too. I did wish someone would give her a bobbypin or two, to keep some of her hair back, but she carried the film well. Her two BFF's, played by Julie Walters and Christine Baranski, are awesome too. The three of them are really fun to watch together. I hope when I have reunions with my girlfriends 10 or 20 years from now, we're that crazy!
An aside - ask Dan Satterfield what he thinks of Meryl Streep if you ever run into him. His answer might throw you for a loop.
Back to the movie. Pierce Brosnan plays "Sam," the leading man who hasn't been in Donna's life for 20 years, and is suddenly back after Donna's daughter, Sophie, invites him and two other men to attend her wedding. One of the three men is Sophie's father, and Donna doesn't know they're coming.
The others two actors (Colin Firth and Stellan Skarsgard) sing very little, and frankly, I wish Pierce would have sang a little less, too. Ladies, we know why he got the role. He looks GOOD.
(But isn't there another handsome leading man out there who tried out for this role, who could sing a little better? He was a little painful to listen to.)
Amanda Seyfried plays young Sophie, the betrothed, and is no doubt the strongest singer in the film. I really enjoyed her performance. She was fun, bright, enthusiastic, all the things a bride should be in the 24 hours leading up to her wedding.
I won't go into what happens in the film, or name all of the players, because you can read that elsewhere, and it's late and I'm tired. Those of you who have seen the play know what happens and if you liked the play, you'll like the movie. (Well, I did, but some out there in web land don't necessarily agree with me.)
Judging on the whole experience, I give it 4 out of 5 stars. Any fun movie musical with a good love story tied in has my support.