GTAIV one of the most overrated games of all time.
In many ways, content was reduced compared to its predecesors, the shooting/cover system was mediocre, there were plenty of glitches, the soundtrack was lacking, and the cellphone was incredibly annoying as hell; every 5 minutes you get called to some boring event which you have to attend or else you'll lose respect/liking.
It doesn't deserve over an 8/10.