“Having gotten the post-”Saturday Night Live” “you can’t break my spirit” thing out of her system with 2005′s “I Am Me,” Ashlee Simpson now just wants to have a good time. And essentially, there’s not much else to take away from “Bittersweet World.” The album finds Simpson trading in guitar pop for a few Timbaland-assisted dance beats—the hitmaker adds his touch to the dark, hypnotic groove of “Murder,” the Pat Benatar-like fist-pumper “Rule Breaker” and the manic “Outta My Head (Ay Ya Ya).” Elsewhere, Simpson goes the cheeky Fergie route with “Boys,” disses teasing girls on “Hot Stuff” and tries out a piano ballad on “Never Dream Alone,” with mixed results. “Bittersweet World” is a party worth attending, but not much is missed if your invite got lost in the mail. —Jill Menze”
