It was a decent show. Our seats were good but they were kind of expensive. My girlfriend and I grew up on this stuff, and the way my gf was singing along and bopping to the music made me happy we were there. I even got up and sang along to a few songs because, if you grew up in the 90s and listened to any popular music, you know all of the songs whether you like it or not.
It's a fairly high energy show, dancing and costumes were colorful and loud. She performed all of her big hits, some of her newer songs, and a lot of her older songs too. I didn't much care about the lip syncing even if it was somewhat obvious. It was still fairly entertaining and some moments were funny. You'll know what I'm talking about when/if you go.
I think 3 stars because tickets are kind of expensive compared to some other shows you could go to in Vegas. You will see pretty much all of her stereotypical fans, women in their late 20s or early 30s, gay men, euros. I guess I know what it would be like being a dad at a One Direction concert.