I see that people have spoken at length about this place. Here are a few pointers that I thought will be useful in addition to what has already been said...
I'm a bit surprised that no one has talked about the rice noodle rolls yet. I would highly recommend this Cantonese stuff (filled with beef/ pork/ shrimp). As opposed to the steel bowls that they use in serving the other steamed items, they serve the rolls in an oval plate and they pour sweet soy sauce on it right before serving.
Be sure to order some green tea with your food because the hot liquid cleanses your palate and is sure to make the glutinous food more enjoyable.
With respect to the desserts it is foolish to order western pastries here. I observed that the Chinese were ordering sweet tofu and mango tofu. We tried the latter and found the taste and consistency to be similar to custard.
You might encounter a couple of waitresses with heavy Chinese accents but do not hesitate to ask someone else for help. There are plenty of people to explain the grub to you.
Visiting the place on Sat/ Sun is especially important because on busy days the restaurant is bursting at the seams and the kitchen is turning a great deal of fresh food all the time. Between 11.30 am and 12.30 pm the wait could be 20-30 mins but there is no waiting for the food after you get a table.
Caveat: please do not turn up in the evening be it any day of the week.... the dim-sum is served only between 11am and 3pm. Of course one can order the other stuff off the menu in the evenings.