I could never get into GTAIV because of this, I loved San Andreas though.
I know what you mean, GTA IV sort of feels like the odd man out.
I happened to truly enjoy the grit and grime of GTAIV.
It's not that I DON'T enjoy the atmosphere. By any other name, the game would be a flawless gem for its time, the problem is, GTA has always been relatively light hearted, and there were some light hearted moments in GTA IV, sure, but its humour was overly toned down compared to Vice City or San Andreas. To some it may be a good thing, or a bad thing, but I felt it removed some of the crass charm GTA has always had.