I've ordered from her quite a few times, and I have never been let down. The 'authentic pad Thai' is super delicious, and I just had the 'pumpkin curry with shrimp' which was so so lush, and had twice as much shrimp as I expected!
Delivery is always fast, and food is always fresh.
It's not the cheapest around, but you're paying for quality.
I can't speak to how 'authentic' the food is, but I can speak to how delicious it is :)