Of the handful of times I've been to CQ, I've always had a positive food experience. It's a no-brainer place to hit up for a reasonably priced delicious Canto styled meal.
Like the other reviews suggested, you must get the fried turnip! It's so good cause it's deep fried cubes of yummy turnip cake. Also the traditional minced pork and century egg congee is cheap and satisfying. I know it's perhaps an overlooked item but I like the tea they serve. It's fragrant and sufficiently steeped.
The quality is consistent and the quantities are good. On a weekend, make sure you go early to avoid waiting. I like a bit of decor where I eat and they have both the good food and the decor which is unlike many Asian eating institutions where the food is the main focus and decor is a last thought.