I've been to a ton of concerts all over the place. I've been to the outdoor side of Stage AE about 6 times now.
Good: Security is on top of things. If people push or act up, they are tossed out. The venue is small so it sets an intimate setting to see a show. Even the lawn isn't that far away. Plenty of air conditioned bathrooms all over.
Bad: It is general admission. Doors usually open at 6:30. People line up to get in before 4. You have to spend that time in line if you want to get up close. The line forms on the side of Bettis' bar. It'll wrap around toward Heinz field. A second line usually forms on the opposite side towards opening time. They let those people in with the front of the main line. They didn't put in the time to wait. Also, they have about 5 security lines and two are for females. Rock shows are about 80% male and girls get to jump the line. I was at a show where the front row center to the one end was 18 people, 16 girls that were from the middle/back of the line. I'm sure bands like that, but fans get screwed. Since it's gen admission, if you're not on the front by the wall, people cut you and there's nothing you can do. The other bad is that if it rains, the line is still long and no matter how close to the stage you are, there is no shelter.