The classic beef burgers are what have made W a popular burger joint, but don't discount the chicken and salmon burgers, which are actually very generous portions of grilled chicken breast and grilled salmon fillets - they taste great and are a very health conscious choice too (particularly if you go for the whole wheat buns).
Sweet potato fries are hit and miss; some days they are thick and tasty, while others they are too thin and almost burnt.
Here is a tip: I usually order many extra toppings on the side and the servers don't seem to mind. Even if all the toppings don't make it into my burger, they make a nice side salad :)