Well, first off, we found that Chinatown in Las Vegas is nothing like Chinatown in San Francisco. It is a bunch of shops and mini-malls spread out along about a two-mile stretch of Spring Mountain Road, west of the I-15.
Joyful House has been listed as one of the best Chinese restaurants in Las Vegas, but in my opinion it's not THE best.
My wife and I and two high-school girls from Shanghai tried it out the other afternoon for an early dinner, and they, at least, seemed to think the food was somewhat authentic. We started out with bowls of West Lake Egg Flower Chowder, which I thought was somewhat bland. Adding a small amount of chili paste and a splash of shoyu (soy sauce) helped.
They ordered steamed chicken with ginger and mustard greens with mushrooms, but didn't seem to eat much of the greens. My wife and I tried the Pan Fried Spinach with Garlic, Barbecued Pork Fried Rice and Chicken Chow Fun. The latter actually wasn't much fun, as the noodles turned out to be really thick and hard to handle. We should have ordered the skinny noodles instead. I thought the fried rice was very good.
Serving sizes here are huge, so we had the leftovers boxed up and we found a couple of homeless guys down the street who really appreciated them.
We could have ordered a bit less and still fed one homeless person, but we got out the door for $95 (including tip) and thought it was quite a bit better than the typical Chinese place.