This is, easily, one of the best brewpubs in the country. You can probably find better beer elsewhere, and you can certainly find more selection and more interesting beers elsewhere (even in Pittsburgh), but the collection of good food, great beer, great atmosphere and a really venerable history.
Sit out on the patio, drink a pilsner and eat some sausage. I don't know that there's a better way to spend an evening in Pittsburgh.