1: The game world is absolutely massive and will push both xbox and PS3 to the very limit in terms of what it has accomplished. Yes, the main city is simply Los Santos however is it AT LEAST 4 times bigger than Liberty City in GTA 4 and that is just Los Santos. The surrounding country side, beaches, etc are massive. For instance, we saw the main character ( an African/American, early 30's) travel by car from the center of Los Santos into the wildnerness and it took over 15 minutes. The views were incredible from farmhouses with cattle, huge wind farms, an oil refinery which appeared to be living and breathing with nearly 100 NPCs working on machinery, operating vehicles, lifting and loaded, etc, unlike the gas works in GTA 4 which seemed to only house a few NPC at a time. The forests are more beautiful than those in RDR and featured people camping, young NPC drinking and dancing around campfires, people riding dirt bikes and jumping over logs, streams, etc. The water effects, forna, plants, trees all looked beautiful.
2: The shooting mechanics have been greatly improved with animations for diving, climbing, rolling and crawling all added for better realism. The re-loading animations for new ammo also look cooler, less static.
3: There is much more climbable elements in the world such as ladders, overhand climbing, etc.
4: There are animals in the game from dogs to cattle but at this time it is not confirmed if you will be able to harm the animals. Rockstar were able to get away with it in RDR as it was a true depiction of the world in which the game was set. Allowing dogs/cattle to die in a game sent in current times may cause headaches with PETA. Its unclear if Rockstar were joking here.
5: There are planes to pilot and they can be crashed into buildings if you choose to do so....
6: Rockstar have included many, many more interior locations such as a shopping mall, college campus, police station, a huge hospital and there is also a vast underground sewer network which one mission later in the game involves a jet ski chase that culminates in a Fugitive-esque waterfall jump ( there are nods to the ridiculous but awesome Ballad Of Gay Tony missions)
7: The city is full of NPCs jogging, weight-lifting, hitting on women, being chased on foot by cops, shopping, washing cars, fixing fences, moving home, filling up their cars, etc.
