I finished the storyline in GTA IV and really enjoyed it although I thought there were too many chase missions or missions that involved chases in some way. That wouldn't be so bad in itself if you could just kill the person you were chasing if you get close enough. But you have to wait til the right moment which is set by the game. It seems ridiculous that you could be right behind someone and shoot them heaps but it won't affect them until the time in the chase they want you to kill that person. Also had quite a few graphical glitches where walls or floors sometimes disappeared and buildings and environments would pop in once I got closer to them. I also had one time where the game crashed mid mission which was very frustrating. Really enjoyed it and I am very happy that I finally finished a GTA, it is probably the first GTA where I have not messed around as much and gone hard at the missions.
Now all I have to decide is do I want to go on to Burnout Paradise or Conan....decisions decisions.