Dawn Treader is my daughter’s favorite book of the series also. She was disappointed by this film. She said that because it wasn’t done by Disney, the animation was not as well done as it could have been. She thought it was too short in length. She also didn’t like the boy actor they chose as Eustis. She liked that Walden Media kept the same four actors as the previous movies. She also thought the sword fight between Edmond and Caspian was well done.
As for Eustace, I thought the actor they selected nailed the role.
Sounds like your daughter had an inclination to have a negative opinion of it because it wasn’t distributed by Disney, for whatever reason, and that clouded her enjoyment of the movie, which is a shame. Walden Media did the first ones distributed by Disney just like they did this one that was distributed by 20th Century Fox, so there was no difference in the animation or who did the animation. It was always Walden Media - it did not go from Disney to Walden Media in who made the film. The distribution / financing just went from Disney to 20th Century Fox. That’s all.