Having flown through 20 different US airports so far in my life I feel pretty comfortable rating PGH INTL four stars. It isn't the most modern facility nor the prettiest but it is a reliable and well-built airport. Last time I checked it was the best de-icing airport in the Northeast (a must in the winter) and rarely does it get shut down due to weather. Allegheny County isn't very "exciting" when it comes to extreme weather (*Knock On Wood*).
Parking coming in and out is clearly marked and accessible. Each of the airlines that flies through PGH has well lit stations for check-in. The only sticking point would be that this is one airport where you HAVE to err on the side of caution when it comes to the time you allot to get across security. I've made lines that I thought would take hours but flew right on through. I've stepped up to shorter lines that took just a long as the longer lines.
Once you're past the hassle part of traveling, checking baggage and making it into the councourses the airport as a lot to offer. There are several outlet stores, a TGI Fridays, a Rite Aid, McDonalds, and a bunch of other eateries. The Councourses also have free WiFI, albeit it depending on how far from the router you end up it can be pretty darn slow. The only qualm I have would be lighting. I think the place feels "grungier" than it really is because lighting isn't as good as it should be.
I hope as airlines consolidate that they consider PGH for more direct flights and even HUB Status.