Be warned. Don't expect the best service ever. It's not the cleanest place you've been in either. The decor is soccer jerseys from places and teams you've probably never heard of. It's divey, eclectic, and authentic.
If you're looking for good Irish food and a cold pint, you can't go wrong at the Pour House. Like most of Carnegie's Main St, this is a hidden gem worth seeking out. They have some of the best Irish food I've had in Pittsburgh- the colcannon is awesome and the shepherd's pie is out of this world. If you're not looking for Irish food, then try the grilled cheese- and make sure you ask it with the three cheeses together. It's big and the cheese is thick and gooey. I get it with a side of potato pancakes... Yum.
Also, they have Guinness, Smithwicks and Harp on tap...