My experience with James Street is limited so bear with me.
A group of us stumbled upon JS after getting to Park House and seeing that it was not open yet. We weren't sure what expect, but were pleasantly surprised with the staff and knowledge of beer. I can't remember the bartenders' name, but she def knew her stuff and was fun to talk to. The owner went out of her way to make sure we were happy and taken care of, even though she spent a good deal of time promoting the bar even though we were from out of town.
The beer selection is pretty good. I did not try any of the food so I can't really comment on that. If / when I come back to Pittsburgh, I'll def visit James Street.