As someone who grew up in Philly....not impressed. Pop's gets props for the Amoroso rolls, but the cheesesteak was completely flooded with cheese whiz and overall lacking in flavor. I love the building though (it's an old converted Wienerschnitzel) and the neon and logo. They do have Tastykakes and Frank's sodas (!), so if you are craving some Black Cherry Wishniak, Pop's is your go-to place.
I'll try Pop's again maybe and get the provolone instead of the whiz, but my initial assessment is that there are better cheesesteaks in this town. Most of the other reviews already have the alternatives covered.