>is it just a general awesomeness of the world?
>is it just the same ol thing with new paint and ppl just love
>that new GTA world feeling we all get every release?

everything about the game is pretty much a given. you know how it will play. you know what the shooting and driving will feel like. you know that you will receive missions in which you will do outlandish things as requested by crazy characters

imo what makes gta games so engaging is the fact that they seem to induce the concept of "avatar involvement"/"getting lost in the game"/"forgetting you're playing a game"/etc. more effectively than any other game. this is accomplished by rockstar creating a highly believable world for you to explore, and letting you do pretty much whatever you want to in that world. you're not beholden to any narrative if you don't want to be. some other games offer this experience but none do it as well as the gta series