I have been here many times. And I have tried quite a few Vietnamese restaurants in North York. I can't speak to authenticity but IMHO this is the only one that is consistent both in their food taste and service, especially after I had some horrible experience at other joints where they served chicken that was unable to chew and charged a hefty price. And the place feels clean every time I am here. Nice atmosphere too.
The only downside can be the parking. Other than that I will highly recommend it to all my friends.