Bob's central complaint here seems to be that combining the abstractness of a musical with the realism of the scenery "just doesn't work." Well, I recognize that this is a matter of opinion, but I saw the movie the other day and I thought it worked fine. I think it's just a matter of going into the movie with the right expectations; I expected realistic scenery combined with people randomly singing at each other, so it fits my expectations perfectly.
His other complaint was that the whole idea of having uncut scenes of the actors actually singing isn't worth showcasing, but I'd say he's missing the point. Shooting the scenes like that makes the emotion feel rawer and "more real." It makes the passion come through more. Some people have complained about the extended uncomfortable close-ups in the movie and I recognize that it's not for everyone, but for people who enjoy musicals for the music will appreciate the raw passion that comes through in those scenes.
The bottom line is that if you like musicals, you will love this movie. If you don't like musicals, you probably will not enjoy this movie. I'd say that Bob's assessment that it "sucks" comes more from the fact that he doesn't like musicals than any particular shortcoming of the film. It wouldn't bother me so much if not for posts like this:
Padwolf said:
It's a shame the film is bad, I really wanted to see it. No doubt I still will go and see it, but if it's so bad it brings Movie Bob's accent out I wouldn't want to waste money D: but I love musicals so much, so I will probably end up liking it by the end.
This is someone who would most likely really enjoy this film who may not actually see it because she took Bob's word for it that it "sucks," and I think that's sad.

For the record, I have many friends who are into musical theatre who enjoyed the movie immensely and highly recommended it. Padwolf, if
you're reading this, I hope you ended up watching the movie.