Well, I didn't really go in expecting anything to be honest. I wanted to see WALL.E, but the ticket machines were bust and the queues were massive. By the time we got to the ticket counter we were too late for that, so my gf convinced me to go and see this instead. As it was basically free, because we have those unlimted membership things, I thought "How bad can it be? I will give it a chance"
I am not making THAT mistake again, I can tell you!
To be fair I don't like musicals, but I have seen others at the theatre, and watched some musical films, and all of them were much, much better than this. Also I quite like ABBA in a kitsch sort of way, so I thought it might be a fun atmosphere like you say, but I'm afraid I just found it too shallow and contrived by far. Maybe if they had made out like the singing was MEANT to be really bad, they could have got away with it, I dunno.