If you go with other Britney fans, you will not be disappointed. Get up, dance, sing along, and enjoy the show. I'd recommend getting mid-level seats. The theater isn't huge, but there are no projectors to show the stage. As others have said, I wish she would have talked a little more or sang one of her slower songs live.
The show is located inside Planet Hollywood. Once inside the venue, you can buy merchandise and drinks. Both are wildly overpriced.