Before going to see Britney, I suggest that one sets their expectations. This is basically a Britney sound track where a woman who resembles Britney is performing on the stage. She does not sing at this concert, but performs her traditional dance moves altered for a woman in her mid 30s.
My wife and myself did enjoy the show. When you see it, you realize that she does have A LOT of hit songs that you will be familiar with. The stage effects are cool, and the venue is a good size where even the cheap seats are "good enough."
This mostly is a 4 star show, but I had to dock a star due to the fact that everything that came out of Britney's mouth was ear piercing. At one point, she put on a horrible brittish accent saying that "it was time to be naughty." Then the accent went on and off for about 30 seconds. Other than that, she said maybe 2 other things and had to us the "F-word" in each sentence. I'm not sure why.
All in all, just go in with lower expectations and you will be good. Hopefully you also don't get a seat behind a tall guy who is there by himself, knows every word to every song, and won't sit down for a moment (even when everybody else is).