I've been known to go well out of my way for dim sum in almost every city I've visited (I even tried in Buenos Aires, to no avail). The reason being that there's such a dearth of dim sum in South Florida that I turn rabid whenever I even get a hint that there may be a decent siu mai close by.
I'd been wanting to try Mr. Chu's on South Beach for a while but heard it was rather expensive for Chinese. Then I found out they added a dim sum lunch. I was there in a flash. First things first, I can't help but compare the place to Tropical Chinese since it's about the only place in Miami for push cart dim sum (Miss Yip doesn't count). In all aspects Mr. Chu's was superior - decor, service, atmosphere. Whereas Tropical's decor just seems tired and in need of a facelift, Mr. Chu's is fresh and clean. Servers are a little overcostumed, but better than seeing servers in stained white shirts.
As for the dim sum, the variety is a little less than Tropical's; however, it is vastly superior. Whereas Tropical's has a frozen food quality, Mr. Chu's seemed fresh. The dumplings seemed lighter, the radish cakes not as greasy. The biggest weakness is in fried items of which there were very little. Better for the arteries I guess.
The restaurant was rather empty for a Sunday but customers trickled in steadily. Given the quality of the offerings and the lack of competitors, I don't see why Mr. Chu's doesn't take the reins on dim sum in Miami.