Sala Thai is great. I've eaten here many times since moving to Madison, and I've always been happy with the food.
On Saturday, I ordered the Yellow Chicken Curry. It was fantastic. It was a generous portion, and they didn't skimp on the chicken. It also had just the right amount of spice. Really fantastic dish, and I can't wait to order it again.
In the past I've had ordered the Pad Thai and a few of their stir fry dishes, and they have always been top-notch. Their eggrolls are also very good. They also have a decent selection of bottled beer and wine.
The restaurant space is nice and cozy, and can get crowded on a Saturday night. Service is always friendly, and while the food doesn't always come out super-quick, it's worth the wait.
They are unfortunately cash-only, so plan accordingly. It is somewhat unforgivable in 2014 to both not accept credit cards AND not have an ATM available in your restaurant. This alone prevents me from giving Sala Thai a full 5-star rating. Otherwise this is really a perfect little Thai restaurant with fantastic food.