Best in series by far!
//Graphics
First off, MUCH, MUCH better than previous GTA's. The graphics are a HUGE improvement in the series with the character models and animation. Niko has all five fingers and uses them very well. Explosions are so fun to do because they look amazing. Crashing cars is always fun because you can make Niko fly out of the vehicle by hitting a wall or something at very fast speeds.
//Gameplay
The gameplay is great, much better than last series. The flow of animations with Niko and other NPCs are beautiful. They flow very well. The controls feel very solid, but I do think that the camera feels alittle bit off with everything else. The driving in GTA IV is alittle bit more difficult because I think I'm just use to the previous driving in past GTAs. Driving feels more realistic.
//Sound
IS FREAKING AMAZING! You can hear everything. I can tell Rockstar has put alot of time into the audio. You can hear the radio when your out the car and other people talking on a cellphone. The voice actoring is perfect and I can see alot of people talking like Niko in the coming weeks.
//Overall
Just buy this game, hands down.