The most annoying glitches are with the targeting system and it's inability to prioritize the obvious target. Oddly, it prioritizes dead, dieing, falling targets the highest, apparently, and neither your distance from a target nor the targets threat to you seem to be even calculated.
It's a shame, because GTA 4 is a really bad shooter and a pretty bad driving game, and those are the two mechanics it uses over and over and over and over in its missions, which usually boil down to "go here, shoot shoot shoot shoot" once you get far enough in the game.
GTA 4 isn't even close to a 10/10. I was arguing this with my girl yesterday -- I said, "I think I'd give this game a 8/10 despite the technical problems and redundancy of the missions". she said, "6/10." We argued a bit, and every time something stupidly outrageous happened that ruined a mission for us, she repeated "6/10". I couldn't rebutt her, because there was nothing to say.
Although I'd still probably give it an 8/10. I've played better games that were released this year, for certain, but it's still pretty fun.
