I think the characters are believable
I just watched this for the first time tonight and then came here to see what everyone else had to say. It seems like a lot of people completely hate Love Never Dies because the characters are different, but I find them totally believable. Ten years have passed since the end of POTO and it seems like pretty much all of them have been through some rough patches. These are the main ones I keep finding complaints about:
Christine/Raoul - over half of all marriages end in divorce. Not to mention, these two didn't know each other for all that long before they got married and most of their relationship was surrounded by drama. It's not super surprising that they ended up being incompatible. Especially considering Christine cheated on Raoul.
Meg - Her life was basically turned upside down when they moved to New York with Erik and she's spent the last ten years trying to win him over and apparently had to resort to prostitution (at least that's what I got from it). That's enough to make anyone crazy.
I'm a completely different person now than I was ten years ago! Why is it so upsetting to everyone that these characters would be different too?