This is some gameplay info if that is relevant...
Recently, Rockstar North President Leslie Benzies conducted an interview with the French Gaming website Jeuxactu. Now today, thanks to Offical Xbox Magazine, we have some English snippits of the interview!
"We want to surprise people with very intense missions from the start. The pace of the game is much faster than any of its predecessors. From the beginning, we want to show off the new game mechanics while creating intense, action-packed gameplay, to capture the player's attention immediately."
"Unlike previous GTA's where main characters such as CJ from San Andreas or Niko were newcomers to the city, Michael, Franklin, and Trevor are not.
They already have contacts, they are integrated with the world and lead a busy life - these characteristics should give players a sense of immediate and total immersion. That said, all three main characters won't be playable from the start. We want to give the player the opportunity to get to know the three characters individually, and explore the world as each of them, and it would not have been possible if all three had been available from the start."