I've been to Hei La Moon multiple times over the past year but had the best experience by far a couple weeks ago with my parents. Hei La Moon, like many other Chinese restaurants in the area, serves Dim Sum as well as the more traditional style lunch/dinner fixings.
The restaurant itself is not actually in Chinatown but about a block away from where the gate is located. There are two floors to the restaurant and I ended up downstairs the last few times I was there. The food, while pretty good, sometimes was a little old (sat around for a while I guess), mainly because I'd been there later in the day (noon-1pm). This past time, I was there around 9:45am and we were seated upstairs. The place was actually pretty empty and the food was super fresh! I think I actually ate more than I should have (which isn't saying much because I always pig out at Dim Sum).
Some of the pictures are posted below :)
I'll try my best to describe some of the dishes, but I mostly know only the Chinese name for them :P