Then I discovered this review on Serious Eats, and frankly, you should just read that instead. There's nothing I can say that Carey Jones hasn't already covered, except to add that Biang! gets the thumbs-up from Apparently Jr, which really does place it in a wholly separate category of awesome. Ask for the buckwheat noodles "not spicy," and hope that your kid is as happy as mine.
If you prefer your restaurant reviews from more traditional sources, here's The New York Times's take.
All I can say is: the springy, ragged, deeply delicious hand-pulled noodles at Biang! have completely ruined Chinese food, and possibly Thai as well, for me. There's no way I can order mediocre lo mein from a neighborhood takeout joint ever again.