@matrix and IIRC all the new content was mostly in separate new locations - like the whole story with aliens and stuff even if it was mostly linear/corridor-like.
I still think that Saints Row 3 managed to make a better GTA than GTA itself ever did, like they get it, they get why people play GTA, Saints Row 4 made it even better. Probably could have been an update/dlc to SS3 but whatever, i like it more.