For a GBA game, Madagascar looks great; it hits all of the major points you'd want a movie-based, kid-focused game to hit. Characters are big and look just like their movie counterparts. But this isn’t a GBA game, it’s for the DS, a much more powerful system than the GBA, so it’s not much of a stretch to want, or really expect, a little more from the game.
Visually, Madagascar definitely goes for the Donkey Kong Country-styled 3D rendered characters rather than more traditional flat 2D sprites. The overall look is good and actually captures the movie's look rather well -- or, as well as can be on a handheld system. Still, the presentation is still good and should appeal to most gamers in the game's target range.
One thing the DS version adds to the game over the GBA version is better, and more varied, voice clips from the characters. Though the quality isn't the best I've heard in a handheld, they're easy to understand and sound like the movie characters, which should delight some kids. Background music fits the game's look, though it's nothing you'll find yourself humming in the shower.