These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Hollywood Homely: Baby swans are more or less identical to ducklings except for feather color.
It's probably more a case of "beauty is in the eye of the beholder" since the other ducks still shun the titular ugly "duckling".
Interestingly, in some versions where the old woman briefly takes him in, she comments on his ugliness, as well.
Unfortunate Implications: The only real reason the cygnet is considered beautiful at the end is because it looks like all the other swans, while originally it was mocked by the other ducklings because it didn't look like them. There's "Beauty is in the eye of the beholder," but there's also "You're only beautiful if you look like everyone else."
The Woobie: The title character. Seriously, who didn't want to hug the poor little guy.