Britney Spears in Las Vegas: Five instant reactions Britney Spears on Friday night began her much-discussed two-year residency at Planet Hollywood Resort & Casino, in which the onetime teen-pop superstar will perform a scheduled 100 shows through 2015, with the possibility of adding more gigs if the production takes off. Singing -- well, sort of -- for what appeared to be a full house at the 4,600-seat Axis Theater, Spears led a show, called "Piece of Me," that married the elaborate razzle-dazzle of old-school Las Vegas entertainment with the jackhammering beats of today's electronic dance music. It was loud, it was colorful, it was over in less than 90 minutes. Pop & Hiss will have a full a review of the show soon, but until then here are five instant reactions. Britney still has friends in high places. On Friday stars including Katy Perry, Selena Gomez, Adam Lambert and Miley Cyrus took in "Piece of Me" from seats close enough to the stage that Spears" dancers did a little back-and-forth with Cyrus during "Get Naked (I Got a Plan)." Later, the "Wrecking Ball" singer was seen singing along to "Till the World Ends" in an Instagram video that quickly went viral. She was wearing a microphone, though it wasn't clear she was using it. Spears" manager and a casino executive have both insisted that "Piece of Me" features live vocals, but Friday the singer appeared to be lip-syncing for the majority of her performance. That went for high-energy dance numbers such as "Womanizer" as well as slower-paced ballads like "Perfume," for which Spears took a seat onstage. The show has plenty to distract you from the vocal question. With various Cirque du Soleil productions running next door (and across the street), Spears clearly felt the need to provide some spectacle, and "Piece of Me" arrives with plenty. In "I Wanna Go" she danced with digitized versions of herself "reflected" on several faux-mirrors -- think Snow White in Sin City -- while "Scream & Shout" featured a pair of neon-clad dancers running on gigantic hamster wheels. And for "Toxic," set in a lush jungle tableau reminiscent of "Avatar," Spears climbed an enormous replica of a tree, then leapt off it wearing wires that carried her toward the audience. Her costume trunk must weigh a ton. The singer opened Friday's show in a version of the bedazzled bodysuit she famously wore in the "Toxic" video, but that was just the first in a series of equally sparkly outfits. Other looks included a bra-and-fedora get-up for "Me Against the Music," a raver's leotard for "Scream & Shout" and, in the beautiful-creepy "Everytime," a flowing white gown affixed with gigantic angel wings. Like many stars, she may not have the best taste in her own music. "Piece of Me" hits most of the high points in Spears" songbook, including the defiant title track, "I'm a Slave 4 U" and her breakout 1998 smash ..." Baby One More Time," which she mashed up here with its 2000 sequel, "Oops! ... I Did It Again." Beyond "Perfume," the only other song Spears played from last month's so-so "Britney Jean" album was its thumping lead single, "Work Bitch." Yet the show also reaches back for a handful of duds -- "Boys," "3," "Do Somethin"" -- any of which might have been replaced with superior cuts from her recent albums. There's no "Radar" here, no "Hold It Against Me," and, perhaps most tragically, no "If U Seek Amy," if u can believe it.