This game is going to be awesome! I'm going to buy a XBOX 360 then I'm buying this game right away! The graphics looks awesome and the creators have said that it's going ot take 1 hour for the player to drive (or walk?) through the city, but they have also said that the city will be smaller than San Andreas (which is the biggest GTA city so far). So we will see, but the details looks great. I recommend a GTA IV trailer detailed video I saw on YouTube. They show you clues of what will be in the game and they also bring up graphical details that are new.
Check that out and also the two trailers (on basically any video site like YouTube or Googlevideos) at
GTA IV's official homepage!