Deal-breaker like "I am greatly disappointed in your Rockstar" or like Actually Not Buying the Game Deal-Breaker?
I'd be disappointed if the area outlying the city was small. Right now it seems to be pretty damn expansive. I'd also be disappointed if they didn't import the Hardcore multiplayer feeling of Read Dead Redemption into GTAV.
I'd actually not buy the game if their intentions to "fix" the driving result in Saints Row 3/Midnight Club or any other Glued to the Ground racing game. Being able to actually screw up and lose control sliding out of control into a wall...that made things actually tense. You had to pay attention to your driving. If we're back to 90 degree turns at 180mph with our eyes closed and our feet on the dash...