Of the 4 Thai places I've tried in Oakville, this is the best and most authentic. I eat there regularly and it's always good. I especially recommend the Drunk Noodles, which most Thai restaurants don't have on their menu but are DELICIOUS. Also, the Panang Curry.
I'd like to point out that I've never had the issues that the below Melanie H. did- mango salad has always been good (the mango isn't supposed to be ripe) and the dishes haven't tasted like they were made of ketchup or out of the freezer.
The only thing I would recommend is that you clarify the spice levels for your dishes- they tend to err on the side of gringo-spice (none), so if you want it spicy, tell them.