What does Torvald's fascination with beauty and appearance imply about his personality? Do his attitudes change at all over the course of the play?
It not only implies that he is shallow, it implies that he is capricious in his emotions. By referring to Nora as his "lark", but paying such close attention to her appearance, her clothing, her eating habits, readers are left with the impression that should she at once become fat, poorly dressed, or unattractive in any way, Torvald would lose interest in her. Nora reinforces this impression through her covert actions and her need to meet his expectations. This attitude, this "capriciousness", does not change at all at the end of the play. He relies on popular opinion. He relies on appearance. When he is in fear of his families' appearance being negative as a result of Nora's actions, he is inflamed and cold towards her. As soon as that fear is relieved, and realizes no one outside the family will know, he is attentive again. He is affectionate again. Nora realizes at this moment what kind of man he has always been, and admits that he is a "strange man" to her. Then, Torvald himself admits he has not changed at all by saying:
"I have it in me to be a different man."
Only at this point does he realize the danger of his attitudes, but as he remains incredulous to the end, and hopeful of Nora's return, readers can not assume that this realization has caused any change.
Torvald's focus on appearance in all of its variations—his wife's beauty, other people seeing it at the party, what things look like ethically vs. what they really are—show a fundamentally shallow personality. However, I don't want to be too hard on the guy. He is not, for example, shown to be markedly shallower than most people. Instead, Ibsen is suggesting that most social mores are relatively shallow.
Do the attitudes change through the play? At the very end of the play, his emphasis on appearances seems to be shredded. I wouldn't go so far as to say he's changed, but his focus is different in the last few pages, and so it doesn't come into play.