My only issue with IV is that Niko’s constant agonising over not wanting to kill people anymore is at odds with the general gameplay of GTA; a game where you’ll probably end up killing at least one innocent person on your way to the mission, let alone the dozen or so cops/criminals you’ll kill during the mission.
The ending really got me though. On my first playthrough I drove around the city for at least an hour real-time trying to decide what to do.