My niece started watching the Monster High webisodes while I was babysitting her one day, and though I acted annoyed then, I found myself watching the rest online that night. I adore Monster High and its anti-bullying messages! Plus the characters are adorable.
In this particular movie, it does a good job of showing kids that just because prejudice has been there for a long time, doesn't mean it's right. Frankie Stein and her friends set out to mend the relationship between Monsters and Normies. My favorite sub-plot is Cleo's difficulty with listening to her family and following her heart. Cleo's father and older sister try to convince her to strike out against the Normies, perpetuating the prejudice, but her boyfriend Deuce knows that's her family influencing her and not what she actually thinks, and tries to help her (He's on Frankie's side throughout the film). Applying this to real life, prejudice of another race, religion, or ethnic group is often passed from parent to child, so it's good for children to see someone have to do the hard thing and go against what their parents say to support what's right.
When it comes to their figures and clothes, I don't think it's a big deal. When I played with Barbies as a kid, I never once thought about her figure, and it's the same for these ghouls. I completely plan on giving my niece her first Monster High doll for Christmas (it'll be Draculaura, her favorite character) :)