I will make this brief. This is not just the best Scottish pub in Pittsburgh, this might be the best pub / bar / restaurant in Pittsburgh - period.
FOOD
Love the scotch eggs but the cardiologist said to only have these once a decade. Stilton and Rasher salad is incredible. Pub burger is the BEST! Reuben and Fish & Chips are excellent. Open face roast beef on italian bread covered with a dark/rich whisky onion gravy and a side of half-mashed red potatoes = ultimate comfort food. So many other great options - you cannot go wrong!
DRINK
Love the beer list. There is a focus on imports but they also have a dozen or so excellent PA craft beers on the list. This place takes everything that they do seriously - the beer tastes fresh and the lines are clean. If you are a fan of scotch whiskey, the list at Piper's Pub cannot be beat - http://piperspub.com/scotch/
SOCCER / FOOTBALL
Fans of the beautiful game rejoice - you have found your home at Piper's Pub. This place is packed during the big games and they get satellite feeds beyond ESPN and Fox Soccer Channel. Every once in a while, I get my boys out of school early and we throw on the EPL jerseys and we go catch an afternoon game at Piper's Pub with other raving lunatic fans. This place is worth a 2 hour drive if you are not in the Pittsburgh area.
Definitely deserving of 5 stars. Love it!