Film is great - it's a perfect story of how treatment in a corrupt hospital prison can deteriorate and break down already broken people, and how people try and use the individual's mental struggle to their own advantage to try achieve something missing from their own life - ending makes a lot of sense as well considering timeline queries raised by the first film.
Don't believe all the negative reviews, you should give it a chance!
Also, calling it a musical is true and false, there are music numbers throughout the film, but the film explains why they are used as a core part of the story and what music can mean to people who live in fantasy worlds to escape their own - there's not just music numbers for the sake of it, do the lyrics always match the story? No, but the songs reflect what the characters are feeling internally at that point in the story.