I doubt it will be as big as they say, they always overstate things.
Also for a monster of a map go check out Just Cause 2
Just curious, when has R* ever exaggerated the size of one of their games? Other developers, yes. R*, not so much.
People need to stop reading into this interior / exterior thing.
What R* said was pretty simple to understand.
"When you include the interior and exterior spaces, Los Santos is bigger than GTA IV, Red Dead Redemption & San Andreas combined, with room to spare". He states - LOS SANTOS only, whether or not that includes the countryside, we don't know yet.
What you can go by are the screenshots and trailer, and by those, it is obvious that the map is at least 3X RDR's map, that alone is hard to comprehend. People who can't grasp the scale of this game by what has been shown so far, won't understand until they actually play it. Then again, some people still think SA is larger than RDR, so.. I guess that doesn't work all the time either..
Is the size being based on the map that comes with the games? RDR's map is more zoomed out than SA's. If you took the RDR map and put it to match the size of say, the width of the roads with SA roads, RDR would be at least a half size larger than SA.
Also, don't even get me started with the whole "cars are faster" routine people use to justify RDR being smaller than it is. Some of those horses can run pretty damn fast, and the difference is that most of RDR's vast desert can be traversed almost in a straight line. In SA you had winding roads and hills and buildings and things that generally made trips take longer. If it had been one straight road you all would've complained about how small the map was. Don't believe me? Get into a biplane (slowest one if I'm remembering correctly) and go from the airfield into the city of Los Santos in a straight line and see how long it takes.