Saw Britney on the 17th with a bunch of girl friends and we were all pretty excited!  We were sadly disappointed in Brit.  She was sloppy and she didn't have much energy.  If she's lip-syncing she should be able to pull off the moves but nope.  I focused on the back up dancers, the stage, props, music, and those were all very well done.  If you're there expecting to see Britney rocking it, you'll be disappointed.