Like most things ABBA, this was equal parts ridiculous and fun. It was a blast seeing it on the big screen in a theater with other people, laughing at some of the (decidedly intentional) corny humor, and then practically dancing in the aisles during the concert scenes, which really are heart of the film.
Can't really be rated as good or bad- it's ABBA, and this is what they do. I loved it.