I spent a long time researching all the dim sum places in Vegas before my visit and settled on Chang's. Great location close to the Strip. I got there @ 10:30 on Friday. I was the 2nd person there. I noticed that while I was there for the next 45 min, I only saw Cantonese customers, a very good sign that the place is authentic.
I don't know if I was one of the first to be there as it opened but the service was uneven. They had two carts loaded but it took them a while to come by. I tried all the usual, shrimp & pork Shu-mai, potstickers, funn-roll (rice crepe-interesting smoky flavor), and finished with sesame balls. All the food tasted very good. My neighbor was having what looked like a bowl of tripe and chicken feet.
All in all a very authentic place with very good dim sum but with uneven service.