HSM: Sing It! takes a different approach to visuals. Rather than trying to create true-to-life versions of the movies stars, it instead takes a cel-shaded approach. This actually works in the game's favor. The Wii isn't known for its graphical prowess and a more realistic approach could end up hurting the game's presentation. All of the characters are recognizable, as are a number of locations from the movie, such as the Drama Club stage. Still, there are a few issues that pop up. Character animation is stiff and comes off a bit flat. However, most of your attention is going to be focused on the pitch meter and words, so little problems like this aren't that noticeable.
When it comes to sound, there isn't much you can say other than you get all of the music from both movies. The quality of the music coming out of the speakers is really good, though really, it's the quality of the music coming out of the player that matters most.