I've had a great time every time I've come to XS. I've never had to wait in the line, which is the reason I'm sure some people would not rate the club highly. But even if you do have to wait a bit, once you get inside it's great. There are inside and outside areas, and you're bound to meet some great people. Everyone is pretty cool and attractive and I've only felt a bit creeped out once (and that was because my friend was really drunk and some guy was "helping").
Overall, definitely one of the clubs I've recommended to people visiting Vegas.