We started the North Shore trail down by Heinz Field and made our way up towards the 31st Street bridge. The trail is relatively flat, with little to no incline shift throughout the stretch we ran. The terrain is paved and crushed/compact gravel, which I do not mind running on. For the most part, the trail is quite wide, but there are sections that get a little tight, especially with bike riders coming through. When you are in and around the apartments, there are some 'blind' spots, so be sure to stay on your side, this will ensure your safety and the safety of anyone riding a bike around those turns.
Starting by the stadiums offers you great views of the city as you run along the river. Once you cross the Clemente Bridge, it starts to get more 'rural' and secluded. It can be quite peaceful until you start coming closer to route 28. Then the noise picks up some.
Overall it is a nice trail for a walk/run/bike ride that offers you a fairly safe run.