The best game so far
Grand Theft Auto IV is of much better quality when compared to its predecessors. It has better graphics, better sound, and better character designs. When you kill somebody, they turn into a ragdoll rather than there being a prerendered animation. In other words, running over someone in this game looks a lot like running over someone in real life. Another thing that I liked was that the car damage is more realistic. For example, if you ran into another car from behind in a previous Grand Theft Auto game, the whole back end would be effected. However, in GTA IV, only the specific spot that you hit would be effected. If you run over a person in GTA IV, their blood will be on your car (another feature not found in other games). Another good aspect that I noticed was the greatly improved character animation. For example, in Grand Theft Auto San Andreas, there was only one facial animation. If a character was angry, their facial expression would stay the same. GTA IV actually gives the characters the ability to change their expression, as well as spread their fingers apart.
My only complaint about this game is that no characters from previous games returned (with the exception of Lazlow, but he's on the radio so he doesn't really count). Although it's true that many of them died, there were a few that didn't such as Phil Cassidy, Wu Zi Mu, or Claude Speed.
The Bottom Line
Overall, I would say that the game is nearly flawless. Longtime fans like me, as well as newcomers would enjoy it. Since it's a whole new story, newcomers could play it without getting confused.