amazing plot that goes for about 30-40 hours (and each hour is filled with an amazing array of awesomeness). Took me 45 hrs to finish.
20+ cars that each handle differently yet predictable.
colorful characters that throw some tough decisions at you
amazing fucking dialog with one of the best voice acting to date
gunfights that you will never forget (last 3 packie missions are the pinnacle of video gaming)
The most detailed city in a video game by fucking far
fun multiplayer (with OT'ers at least)
Niko - one of the best protagonist ever made in any fucking medium (When you start genuinely caring for the guy you control, that's special)
humor which pokes fun at every race, nationality and social status (not to mention every car, beer, company ever made). Niko is witty as fuck too.
radio that owns regardless of your taste.