Think of it this way.
GTA3 is super boring in retrospect. But they used that framework to make GTA: Vice City which was super awesome, and then GTA: San Andreas, which was mindblowing.
GTA4 is super boring in retrospect(And for most, when they played it), but Ballad of Gay Tony was rockin'. Lost and the Damned was... okay.
GTA5 is looking to be this generation's San Andreas.
Also, I am so torn. I really, really, really want GTA5, but at the same time,
I think I'm gonna get GTA5 first, but god damn, Saint's Row 4 also looks super rockin'.