Overall, PIT is a good airport. Given that it was built for much higher traffic, everything is far under capacity.
However, the Delta flight from Paris continues to be very inconvenient and the process of arrival is designed in a very stupid manner; after our first time on this flight, we decided not to do it again but we broke down because there was a rare deal on this route. One would think that PIT's only flight to Europe would be outstanding. It is excellent to CDG. Upon return, one goes through customs and immigration as expected but then stupidity gets inserted into the process.
The idiotic design flaw is that one must recheck bags and go through security in order to LEAVE THE AIRPORT. This is standard procedure for connecting flights but not if your final destination is PIT. I have traveled numerous airports on three continents regularly and never seen anything as stupid as this process. Third world countries do better. Imagine you purchased some duty free booze in CDG Paris. You cannot bring them through security and they need to be placed into your baggage. Our first time on this flight, we were not told to put the liquor into our bags. Several people forfeited very expensive wine because they already checked their bags. They do a better job of warning passengers now.
Additionally, Delta seems to have some problems with baggage. We rechecked three bags after clearing customs for pickup at the baggage claim so we could leave the airport. One bag arrived fairly promptly, about 20 minutes after checking it. The other two bags showed up more than 45 minutes after the first. All were deposited on the conveyer belt at the same time. They only had to move the bags from the gate to the "landside terminal". Delta told me that they have three flights arriving very close together and there are only so many baggage handlers. These three flights all came in on schedule. They knew the planes and passengers would arrive - no mystery regarding the required tasks.
The international arrival area was designed when security was far more lax than it is now however there are solutions. Why not run buses? European & Asian airports are always loading passengers into buses. Why not move the international gate to the "land side terminal"? It is simply not worth the trouble to get a direct flight. We intend on driving to another airport to do international flights or simply connecting. PIT management and facilities are not competent to handle international flights.