I'm a wine professional, living in Bangkok and travelling frequently throughout South East Asia. I'm a huge fan of Laos and Cambodia and off the beaten track travel. Feel free to contact me at: www.facebook.com/mil.elephants
When a place has a Michelin star or three, or anyone associated with a restaurant has one, your expectations go up significantly. Even though Tim Ho Wan has such accolades (in Hong Kong) it isn't one of those places you need to take out second mortgage for a table for two. In this regard, it's definitely worth a small investment to experience something with such a great reputation.
My points of reference for Dim Sum are Momofuko in New York, basically for their incredible pork buns and also Tom Ho Wan in Hong Kong. However the beauty of Dim Sum is that it's open to a combination of tradition and innovation.
Having lived in Asia for a long time, I usually look for something new and challenging on a menu. Tim Ho Wan is great for this. Broccoli in an Abalone Scallop Sauce, Congee with Century and Salted Egg, and Rice with Chicken Sausage and Mushroom. All were well balanced and showed creative use of classic ingredients. Congee is much underrated and should have a more prominent place on Asian menus in Australia.
But you also have to try the buns. I know a lot of people are surprised by the sweetness of many pork dishes in Asia, and the Baked Buns at Tim Ho Wan are no exception. It's a matter of taste and most Asian societies have a sweet tooth, so this is only to be expected.
While I'm still a huge fan of Momofuko's pork buns above all, the quality and intensity of flavour in this one is top notch. Sure it's a different style being baked and not steamed, but both buns are extremely memorable.
Generally I'm not inclined to eat in restaurants with multiple outlets, but I'll make an exception for Tim Ho Wan. If you do go, try something different and you might just be surprised.
Finally, for the quality of food, it's really good value.