Hilary Duff's debut, Metamorphosis, is what teen pop should sound like in 2003. It picks up on mainstream trends, particularly those spearheaded by Avril Lavigne, but turns them light and sweet, making for a very good modern bubblegum album. One of the keys to its success is that Duff is never sexed up, the way that Britney Spears was right from the start of her career. This is also true of Hilary in her acting career, since her TV alter ego, Lizzie McGuire, is a regular teenager with teenage concerns, including (but not limited to) crushes on unattainable boys, getting along with her pest of a little brother, understanding her parents, worrying about money, and negotiating the cliques at her school. Metamorphosis is the musical equivalent of Lizzie McGuire, only splashier and savvier and not as silly or Disneyfied as the show. In other words, it's the sound of a preteen turning teenager, finding inspiration in the tough-girl pose of Avril but also being in the fortunate position of being able to work with the Matrix as well. The three songs helmed by the Matrix -- "So Yesterday," "Where Did I Go Right?," and "The Math" -- bear their trademark beats, acoustic guitars, and ridiculous spoken interjections, and they all sound a bit more natural coming from a teenager than they do coming from, say, Liz Phair, but Avril's influence can be heard throughout the record, particularly in how Duff has absorbed how Lavigne appeals to average girls while singing insidiously catchy songs. Hilary does that here, too, but she has a sweeter, more appealing voice than Avril, and the rest of the record follows her cheerful charisma, resulting in a charmingly effervescent listen. While some songs shine brighter than others, there is no dullness here, and the whole thing clocks in at a breezy 43 minutes, which helps keep things light and engaging. Metamorphosis isn't a record that will change the world, but like the best teen pop, it sounds right in its moment, which means it's about as good as this kind of music gets.