Ashlee Simpson's position in the big leagues is assured with BITTERSWEET WORLD, an album that finds her working with superstar producers Timbaland and Chad Hugo of the Neptunes. Simpson's choices for production help can be heard in the club-oriented, party atmosphere of the album, especially on tracks like "Rule Breaker" and "Murder." <p>BITTERSWEET WORLD also nods to female-fronted New Wave acts of the 1980s such like Pat Benatar and Missing Persons. The wiry, guitar-driven sounds of "Outta My Head (Ay Ya Ya)" and "Ragdoll" surge with an energy that is both retro and contemporary, creating a nice balance with the more R&B-flavored tracks. But Simpson never turns her back on pure radio-ready pop either, as the lead-single "Little Miss Obsessive" proves.