Lotus of Siam tastes Authentic but the price sure isn't. I've been to the Best Place in NYC (SriPhadPhai) and the prices are half of Lotus of Siams.
The Bacon wrapped Shrimp were Okay.
The Veggie Tom Yum delicious, as was the Chicken Pad Thai.
The Food here is AWESOME.
Be forewarned, on a scale of 1-10, a 6-7 will make someone with a high spice tolerance teary eyed- to the point you won't taste your food.